This marshmallow fluff peanut butter fudge comes from my great-grandma's holiday recipe collection. It is creamy, sweet, old-fashioned, and made with sugar, milk, light corn syrup, peanut butter, marshmallow creme, butter, and vanilla.
I am slowly working through my great-grandma's handwritten holiday recipes, and this peanut butter fudge is one of the recipes that instantly feels like Christmas. It is the kind of fudge that belongs on a cookie tray next to old-fashioned cookies, bars, and little pieces of candy wrapped up for neighbors.
The original card includes cocoa powder for a darker version, but I made this batch without cocoa. That gives it more of a creamy peanut butter marshmallow flavor instead of chocolate peanut butter fudge.
This is not a microwave fudge or a two-ingredient shortcut. It is an old-fashioned peanut butter fudge recipe where you cook the sugar mixture first, then stir in the peanut butter and marshmallow fluff until the fudge turns pale, thick, and creamy.
The main trick is cooking the sugar mixture long enough for the fudge to set, but not so long that it turns dry or crumbly. Once you understand soft-ball stage, this recipe is very doable.
Why This Recipe Works
This peanut butter fudge works because the sugar mixture is cooked before the peanut butter and marshmallow creme are added.
The cooked sugar, milk, and corn syrup create the base of the fudge. The peanut butter gives it flavor and richness, while the marshmallow fluff helps make it creamy and easier to slice.
A lot of fudge recipes fail because the sugar mixture is either undercooked or overcooked. Undercooked fudge can stay soft. Overcooked fudge can turn hard, dry, or crumbly.
That is why the soft-ball stage matters.
What Is Marshmallow Fluff Peanut Butter Fudge?
Marshmallow fluff peanut butter fudge is a creamy peanut butter fudge made with marshmallow fluff or marshmallow creme.
The marshmallow fluff helps the fudge set with a smoother texture. It also gives the fudge that sweet marshmallow flavor that works really well with peanut butter.
Some recipes use marshmallow fluff. Some use marshmallow creme. Some use mini marshmallows. They are all similar, but marshmallow fluff or marshmallow creme is usually the easiest because it melts smoothly into the hot sugar mixture.
Marshmallow Fluff vs Marshmallow Creme
Marshmallow Fluff and marshmallow creme are very similar and can usually be used the same way in peanut butter fudge recipes.
Marshmallow Fluff is a brand name, while marshmallow creme is the more general name. Both are thick, sweet, spreadable marshmallow products.
For this recipe, either one works. Use about 2 cups of marshmallow creme or fluff.
If you only have mini marshmallows, you can use them, but they need to fully melt into the hot mixture before the fudge is spread into the dish.
The Soft-Ball Stage Strategy
The most important part of old-fashioned peanut butter fudge is cooking the sugar mixture to soft-ball stage.
Soft-ball stage means the hot sugar mixture has cooked long enough to form a soft ball when dropped into cold water. If you use a candy thermometer, this is usually around 234°F to 240°F.
Grandma's card uses the old-school cold water test. You drop a small spoonful of the hot sugar mixture into cold water. If it forms a soft ball that holds together but still feels pliable, it is ready.
If the syrup dissolves into the water, it needs more time.
If it turns hard in the water, it has cooked too long.
Full Rolling Boil vs Gentle Boil
For fudge, a full rolling boil means the mixture keeps bubbling even while you stir.
A gentle boil may not cook the sugar mixture quickly enough. That can leave you with fudge that tastes good but does not set firmly.
Once the mixture reaches a full rolling boil, keep a close eye on it. Use a timer if your recipe uses minutes, or use a candy thermometer if you want more control.
For this recipe, the cold water test is the best guide because that is how the original card was written.
Why You'll Love This Recipe
- Great-Grandma's Recipe: This comes from a handwritten family holiday fudge card.
- Classic Peanut Butter Flavor: Creamy peanut butter gives the fudge a rich, old-fashioned taste.
- Made with Marshmallow Fluff: Marshmallow creme helps the fudge set smooth and creamy.
- No Cocoa Version: This version skips the cocoa for a lighter peanut butter marshmallow flavor.
- Perfect for Christmas: This is the kind of fudge that belongs on a holiday cookie tray.
- Big Batch Recipe: It sets in a 9×13 dish, so it makes plenty of pieces of fudge to share.
- Make-Ahead Friendly: Fudge stores well, which makes it great for holiday baking.
Ingredients You'll Need
Sugar: The base of the fudge. It gives the candy its sweetness and structure.
Milk: Helps dissolve the sugar and cook the fudge base.
Light Corn Syrup: Helps keep the fudge smoother and reduces the chance of graininess.
Butter: Adds richness and helps round out the flavor.
Vanilla: Adds warmth and makes the peanut butter flavor taste better.
Creamy Peanut Butter: Gives the fudge its main flavor. Standard creamy peanut butter works best.
Marshmallow Fluff or Marshmallow Creme: Helps create a creamy texture and classic marshmallow peanut butter flavor.
Cocoa Powder, Optional: The original card includes cocoa powder for a chocolate version, but this no-cocoa version is focused on peanut butter marshmallow fudge.
Best Peanut Butter for Peanut Butter Fudge
Use standard creamy peanut butter for the smoothest fudge.
I do not recommend natural peanut butter for this recipe. Natural peanut butter can separate, which may make the fudge oily or keep it from setting correctly.
Crunchy peanut butter can work if you want texture, but creamy peanut butter gives the most classic holiday fudge bite.
Equipment You'll Need
Medium Saucepan: Use a medium saucepan with enough room for the sugar mixture to boil.
Wooden Spoon or Silicone Spatula: You need something sturdy for stirring the hot sugar mixture and beating in the peanut butter and marshmallow creme.
Candy Thermometer: Optional, but helpful if you want to check soft-ball stage by temperature.
Small Bowl of Cold Water: Needed if you use the old-fashioned cold water test.
9×13 Dish: This recipe makes a larger batch and sets well in a 9×13 dish.
Parchment Paper: Helpful for lifting the fudge out of the dish before slicing.
How To Make Marshmallow Fluff Peanut Butter Fudge
1. Prepare the dish
Grease a 9×13 dish or line it with parchment paper.
Have the peanut butter, marshmallow fluff, butter, and vanilla measured before you start. Fudge moves quickly once the sugar mixture is ready.
2. Cook the sugar mixture
Add the sugar, milk, and light corn syrup to a medium saucepan.
Cook over medium to medium-high heat, stirring often, until the mixture reaches a full rolling boil.
Continue cooking until the mixture reaches soft-ball stage, about 234°F to 240°F, or until a small drop forms a soft ball in cold water.
3. Remove from heat
Once the sugar mixture reaches soft-ball stage, remove the pot from the heat.
Do not overcook. Overcooked fudge can become hard or crumbly.
4. Add butter and vanilla
Stir in the butter and vanilla.
The hot mixture will melt the butter quickly.
5. Stir in peanut butter and marshmallow fluff
Add the creamy peanut butter and marshmallow fluff.
Stir with a wooden spoon or sturdy spatula until everything is melted, smooth, and fully combined.
6. Beat until pale and thick
Beat the fudge by hand until it turns lighter in color and starts to thicken.
Grandma's card says to beat until it becomes pale, almost like marshmallow cream.
7. Spread into the pan
Quickly spread the fudge into the prepared 9×13 dish.
Smooth the top before it starts to set.
8. Cool and slice
Let the fudge cool at room temperature until set.
Once firm, lift it from the pan if using parchment paper, then slice into small squares.
How Long Does Marshmallow Fudge Take To Set?
Marshmallow fluff peanut butter fudge usually needs at least 1 to 2 hours to set at room temperature.
If your kitchen is warm, you can place the dish in the fridge after it cools slightly. The fridge helps firm it up faster, but do not slice it until it is fully set.
For clean pieces of fudge, let it cool completely before cutting.
Why Is My Peanut Butter Fudge Soft?
Soft fudge usually means the sugar mixture did not cook long enough.
If the mixture does not reach soft-ball stage, the fudge may taste good but stay too loose to slice cleanly.
Other reasons fudge can stay soft:
- The mixture did not boil long enough.
- The heat was too low.
- Too much liquid was added.
- Natural peanut butter was used.
- The fudge was sliced before it fully cooled.
Why Did My Fudge Turn Grainy?
Grainy fudge usually comes from sugar crystals.
To help avoid grainy fudge, use a heavy or medium saucepan, stir carefully, and avoid scraping sugar crystals from the sides of the pan back into the fudge.
The light corn syrup in this recipe also helps reduce graininess and keeps the texture smoother.
Why Did My Fudge Get Hard or Crumbly?
Hard or crumbly fudge is usually overcooked.
Once the sugar mixture reaches soft-ball stage, remove it from the heat. If it cooks past that point, too much moisture evaporates and the fudge can become dry.
That is why grandma's card says not to overcook.
Can You Make Peanut Butter Fudge With Marshmallows Instead of Marshmallow Creme?
Yes, but marshmallow creme or marshmallow fluff is easier.
If using mini marshmallows instead of marshmallow creme, stir them into the hot sugar mixture until they are completely melted. Any unmelted pieces can leave the fudge uneven.
As a general swap, a 7-ounce jar of marshmallow creme is often used in place of about 1 1/2 to 2 cups of mini marshmallows, depending on the recipe.
Can You Make Peanut Butter Fudge Without Marshmallow Fluff?
Yes, but it becomes a different style of peanut butter fudge.
Some peanut butter fudge recipes use powdered sugar. Others use sweetened condensed milk. This old-fashioned version uses marshmallow fluff because it helps create a creamy texture and classic holiday fudge flavor.
If you leave out the marshmallow fluff, you will need a different recipe formula.
Is Peanut Butter and Marshmallow Fluff Called a Fluffernutter?
Yes. Peanut butter and marshmallow fluff together are often called a fluffernutter, especially when used in a sandwich.
This fudge has that same peanut butter marshmallow flavor, which is why some people call it fluffernutter fudge.
Troubleshooting & FAQ
How do you make easy peanut butter fudge?
Easy peanut butter fudge is usually made by cooking a sugar base, then stirring in peanut butter and marshmallow fluff until smooth. This version uses sugar, milk, corn syrup, peanut butter, marshmallow creme, butter, and vanilla.
How do you make old-fashioned peanut butter fudge?
Old-fashioned peanut butter fudge is usually cooked on the stove until the sugar mixture reaches soft-ball stage. Then peanut butter and flavorings are stirred in before the fudge is spread into a dish to cool.
What is the secret to perfect fudge?
The secret is cooking the sugar mixture to the right stage. Undercooked fudge may not set, while overcooked fudge can turn dry or crumbly.
What causes fudge not to get hard?
Fudge usually does not get hard if the sugar mixture was undercooked. It needs to reach soft-ball stage so it can set properly after cooling.
Can I use marshmallows instead of marshmallow fluff for fudge?
Yes, but marshmallow fluff or marshmallow creme melts more smoothly. If using mini marshmallows, stir until completely melted.
Can I substitute marshmallow creme for Marshmallow Fluff?
Yes. Marshmallow creme and Marshmallow Fluff can usually be used the same way in peanut butter fudge.
Are you supposed to refrigerate Marshmallow Fluff after opening?
Check the label on your jar. Many people store opened marshmallow creme tightly covered at room temperature, but the best storage method depends on the brand.
How long does marshmallow fluff fudge last?
Store marshmallow fluff peanut butter fudge in an airtight container for about 1 week at room temperature. For longer storage, keep it in the fridge or freezer.
Should fudge cool at room temperature or in the fridge?
Let the fudge start cooling at room temperature first. Once it is no longer hot, you can move it to the fridge if you want it to set faster.
Can you freeze peanut butter fudge?
Yes. Wrap the fudge tightly or place it in an airtight freezer-safe container. Freeze for up to 2 months. Thaw before serving.
Substitutions & Variations
| Component | Swap Options |
|---|---|
| Marshmallow Fluff | Marshmallow creme or melted mini marshmallows |
| Creamy Peanut Butter | Crunchy peanut butter for texture |
| Milk | Evaporated milk, though texture may change |
| Light Corn Syrup | Honey can work, but flavor and texture may change |
| Vanilla | Maple extract or almond extract |
| No Cocoa Version | Keep as written for peanut butter marshmallow fudge |
| Chocolate Version | Add cocoa powder from the original recipe card |
| 9×13 Dish | Use an 8×8 or 9×9 dish for thicker pieces |
Storage and Freezing
Store fudge in an airtight container at room temperature for about 1 week.
For clean layers, place parchment paper or wax paper between stacked pieces of fudge.
If your kitchen is warm, store the fudge in the fridge. Let it sit at room temperature for a few minutes before serving so it softens slightly.
To freeze, wrap the fudge tightly in plastic wrap, then place it in a freezer-safe bag or container. Freeze for up to 2 months.
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The Final Verdict & Share
This marshmallow fluff peanut butter fudge is sweet, creamy, and straight from my great-grandma's holiday recipe collection. I made the no-cocoa version for a lighter peanut butter marshmallow flavor, but the original card also leaves room for a chocolate version. Make it once for Christmas, slice it into small pieces, and tag me if you try it.
Grandma's Marshmallow Fluff Peanut Butter Fudge
Ingredients
- 4 cups sugar
- 1 cup milk
- 1/2 cup light corn syrup
- 4 tbsp butter
- 1 tsp vanilla extract or to taste
- 2 cups peanut butter creamy peanut butter works best
- 2 cups marshmallow cream or Marshmallow Fluff
Equipment
Method
- Grease a 9×13 pan or line it with parchment paper.
- Add the sugar, milk, and light corn syrup to a medium saucepan.
- Cook over medium to medium-high heat, stirring often, until the mixture reaches soft-ball stage, or until a small amount forms a soft ball when dropped into cold water.
- Remove from heat as soon as the mixture reaches soft-ball stage. Do not overcook.
- Add the butter and vanilla extract. Stir until the butter melts into the hot sugar mixture.
- Add the peanut butter and marshmallow cream.
- Beat by hand with a wooden spoon until the fudge turns pale, thick, and fully combined, similar in color to marshmallow cream.
- Quickly spread the fudge into the prepared 9×13 pan.
- Let the fudge cool completely at room temperature until set.
- Slice into small pieces and serve.
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