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These Disappearing Marshmallow Brownies are full of chocolate chips and a have pockets of melted marshmallows scattered throughout, making these bars chewy and irresistible!!
This recipe came from an old, well-loved church cookbook and my mom has been making it for as long as I can remember. They are chocolate-y and have the best chewy texture, thanks to the “disappearing marshmallows!”
Ingredients Needed
- Butterscotch Chips
- Butter – I normally use salted butter, but unsalted will work fine.
- All Purpose Flour
- Brown Sugar – Both light and dark brown sugar will work, the dark might make them slightly more chewy.
- Baking Powder & Salt
- Vanilla – Pure vanilla extract or imitation vanilla works.
- Eggs – Large eggs are typical for baking.
- Mini Marshmallows – Make sure you don’t purchase the marshmallow “bits.” You need the soft, mini marshmallows.
- Chocolate Chips – I prefer regular sized semi-sweet, but milk chocolate would work too.
- Chopped Nuts – These are optional, but I recommend chopped walnuts or pecans!
How to Make Disappearing Marshmallow Brownies
First you’ll want to preheat the oven to 350F and line your pan. I recommend spraying the pan and then lining it with parchment paper, leaving extra paper to hang over the edges to more easily remove the bars after baking.
Microwave the butterscotch chips and butter until smooth. Make sure to stop and stir frequently.
Pour the butterscotch mixture into a large bowl and mix in the dry ingredients.
Add the vanilla and eggs and stir until smooth. Then, fold in the marshmallows, chocolate chips, and nuts if you are using them, until just combined.
Carefully spread the thick batter into the lined pan with a spatula, making sure to keep the paper in place.
Bake for 20-25 or until the edges are set. The center will still be jiggly, but once cool it will become firmer.
To remove the cooled bars, run a knife around the edges of the pan. Then, use the extra parchment paper as a handle and remove them from the pan for easy cutting!
How to Know When these Bars are Done
The simplest way to tell the bars are done is by looking at them! The top should be golden brown and the center will be slightly jiggly right out of the oven.
The best way to know if they are done is by checking them with a thermometer. To ensure the eggs in the brownies are fully cooked (and the bars are safe to eat), the center should be 160F. Do not touch the thermometer to the bottom of the pan, and if possible, ensure the thermometer is not in one of the mix-ins as that temperature will likely read differently. If you do not have a thermometer, I highly recommend this one or this one. They are useful for all sorts of recipes in the kitchen.
Frequently Asked Questions
In the oven, the marshmallows slowly melt into the surrounding batter, leaving marshmallow-lined holes in the bars and a delicious taste!
The leftovers can be stored in an airtight container at room temperature for a couple of days for best quality. After that they will begin to stale.
…If you are curious about what makes baked goods go stale, look up retrogradation and syneresis! It’s a pretty cool process… for this food scientist at least. 🙃
Yes! You can halve the recipe. I recommend using an 8×8 inch pan. The cooking time may be a bit shorter.
Other Bar Recipes I Recommend
- Best Ever Scotcheroos
- No Bake S’mores Bars
- Peanut Butter Bars
- Oh Henry Bars
- Butterscotch Brickle Bars (my personal favorite)
Disappearing Marshmallow Brownies
Ingredients
- 1 cup butterscotch chips
- 1/2 cup butter
- 1 1/2 cups flour
- 2/3 cup brown sugar
- 2 teaspoon baking powder
- 1/2 teaspoon salt
- 1 teaspoon vanilla
- 2 eggs
- 2 cups mini marshmallows
- 2 cups semi-sweet chocolate chips (milk chocolate is fine too)
- 1/2 cup chopped walnuts or pecans optional
Instructions
- Preheat oven to 350°F.
- Line a 9×13 pan* with parchment paper (or spray with cooking spray).
- Add the butter and butterscotch chips to a microwave-safe bowl. Microwave until smooth, stirring frequently.1 cup butterscotch chips, 1/2 cup butter
- Pour the butterscotch mixture into a large mixing bowl. Add the flour, brown sugar, baking powder and salt.1 1/2 cups flour, 2/3 cup brown sugar, 2 teaspoon baking powder, 1/2 teaspoon salt
- Add the vanilla and eggs and stir until smooth.1 teaspoon vanilla, 2 eggs
- Gently stir in the marshmallows, chocolate chips and nuts (optional) just until combined.2 cups mini marshmallows, 2 cups semi-sweet chocolate chips, 1/2 cup chopped walnuts or pecans
- Spread into your prepared pan and baked for 18-22 minutes. Do NOT overbake.
- The center will be jiggly, but will become firm when cool.
Notes
Nutrition
NOTE: Blog post updated in 2025 to include new photos and make the writing more streamlined and helpful. (Original photos below!)
