These Disappearing Marshmallow Brownies are a rich and flavorful treat, with butterscotch and chocolate chips, plus puffy marshmallows. Once baked, the marshmallows melt into the bars, creating little pockets of ooey-gooey chewiness – it’s the most wonderful, fun texture!
These Disappearing Marshmallow Brownies (some people call them Butterscotch Bars) are a simple, yet special, baked treat. Straight from my childhood, this 9×13 pan of irresistible goodness was a regular at our house, thanks to Mom (she also made many pans of Mint Chocolate Brownies and Fudgy Brownies). This is the best kind of throwback recipe: easy, made with a relatively short list of ingredients, and DEEEEEEELICIOUS!
What Makes These Disappearing Marshmallow Brownies a Hit
Recipes that stand the test of time always win! Here’s why my mom’s bars are still a favorite:
- A fun change of pace. There are countless chocolate and vanilla and caramel treats in this world, but butterscotch? We just don’t see a lot of this flavor. If you’re a butterscotch fan, also try my Butterscotch Chocolate Chunk Blondies with Smoked Salt!
- Awesome flavors and textures. These bars are soft and chewy and buttery, in the most delightful, yummy way. The disappearing marshmallows are truly the magic ingredient here. (Marshmallows also disappear into my Chocolate Fondue.)
- Comes together in a snap. This recipe is dangerously easy to make. You don’t need a stand mixer or even a hand mixer—just melt the butter and butterscotch and stir everything else together.
What You’ll Need
Here’s a quick rundown of the ingredients you’ll need to make these irresistible butterscotch bars. Scroll down to the printable recipe card to find the exact ingredient quantities and recipe instructions.
- Butter – Unsalted butter adds richness and moisture to the recipe, making it super delectable!
- Butterscotch chips – You can find these in the baking aisle alongside chocolate chips.
- Flour – All-purpose flour gives the bars their structure.
- Brown sugar – Light brown sugar adds sweetness and a hint of rich molasses flavor.
- Baking powder – To help the bars rise.
- Salt – I use Morton kosher salt in my baking.
- Vanilla extract – Adds a warm, sweet aroma. Use pure vanilla extract, not imitation, for the best flavor.
- Eggs – These add rich flavor and texture, plus help bind the bars together.
- Marshmallows – Mini marshmallows add a gooey texture and sweetness, just like they do in my Marshmallow Popcorn Balls. If you happen to have large marshmallows on hand, you can cut them into smaller pieces with kitchen shears.
- Chocolate chips – I use semisweet chocolate chips.
How to Make Disappearing Marshmallow Brownies
Follow these simple steps to whip up disappearing marshmallow brownies!
- Prepare. Preheat your oven to 350° F and lightly spray a 9” x 13” pan with non-stick spray.
- Create butterscotch mixture. Add the butter and butterscotch to a saucepan and melt them over medium-low. Remove from heat and let the mixture cool until lukewarm. Then stir in the vanilla and eggs.
- Mix the dry ingredients. Whisk the flour, brown sugar, baking powder, and salt in a bowl.
- Combine wet and dry. Stir the dry ingredients into the wet butterscotch mixture.
- Add the inclusions. Fold in the marshmallows and chocolate chips.
- Transfer to pan. Spread the mixture into the pan. It will be thick.
- Bake. Place the pan in the oven and bake for about 20 minutes, or until the edges are lightly browned. Cool completely before slicing and serving.
Tips & Variations
Here are some tips and variations for these disappearing marshmallow brownies.
- Be patient. Let the melted butterscotch mixture cool before folding in the chocolate chips and marshmallows. Otherwise, these additions will likely melt together as you fold the mixture together, and you will lose the desired texture.
- Use your favorite inclusions. You can experiment with other add-ins if you’d like, as long as you keep the ratios the same. For a more pure butterscotch flavor, you can fold in additional butterscotch chips instead of chocolate. Or try adding chopped nuts for crunch.
- Underbake them slightly. I pull these bars out of the oven when they’re set on the sides, but still a little gooey in the center. They’ll get more solid as they cool, but this gives them a fantastic fudgy, chewy texture.
- Cut the recipe in half. My mom’s original recipe was for a smaller pan, and I adjusted it for a 9×13-inch pan. If you’d like to halve the recipe, just use an 8×8-inch pan – it should take a bit less time to bake.
Serving Suggestions
These bars are rich and decadent, the kind of dessert that’s best served with a cold glass of milk! A coffee would also be great.
How to Store
- Room temperature: You can store these disappearing marshmallow brownies at room temperature in an airtight container for up to 5 days.
- Freezer: These bars freeze well. Just place them in an airtight container, with parchment paper separating any layers, store in the freezer for up to 3 months. Thaw them at room temperature or warm them up in the microwave for a melty, gooey treat that tastes like it came fresh out of the oven!
More Bar Recipes to Bake
Disappearing Marshmallow Brownies
Yield: 16 bars
These Disappearing Marshmallow Brownies are rich and flavorful, with butterscotch and chocolate chips, plus puffy marshmallows that melt into the bars and give the most wonderful texture!
Print
Ingredients
- ½ cup unsalted butter
- 1 cup butterscotch chips
- 1½ cups all-purpose flour
- ⅔ cup packed light brown sugar
- 2 teaspoons baking powder
- ½ teaspoon Morton kosher salt
- 1 teaspoon pure vanilla extract
- 2 large eggs
- 2½ cups mini marshmallows
- 2 cups semi-sweet chocolate chips (I use Guittard brand)
Instructions
- Preheat oven to 350°F. Lightly spray the bottom and sides of a 9'' x 13'' pan (I like to use a light-colored metal pan) with non-stick spray and set aside.
- In a large saucepan over medium-low heat, melt butter and butterscotch chips, stirring constantly. Do not let the mixture darken. Don't worry if it looks grainy or separated; it'll still work! Remove from heat – let cool until mixture is only lukewarm (you'll be adding marshmallows and chocolate chips, and don't want them to start melting before going in the oven).
- In a medium bowl, whisk together flour, brown sugar, baking powder, and salt.
- Once the butterscotch mixture is the slightest bit warm, add vanilla and eggs, and stir well to combine. Then add the flour mixture and stir to combine.
- Quickly and gently fold in marshmallows and chocolate chips, until just combined. Do not over stir.
- Spread mixture into prepared pan and bake for about 20 minutes or so, taking care to not over bake. (I think they're best when just slightly under-baked!) The edges should be nicely browned, and the center not quite set. The bars will firm up as they cool.
- Let cool COMPLETELY before cutting into individual bars.
Notes
from Mom’s recipe box
Nutrition Information:
Serving: 1 Calories: 318kcal Carbohydrates: 44g Protein: 3g Fat: 16g Saturated Fat: 10g Polyunsaturated Fat: 5g Cholesterol: 39mg Sodium: 164mg Fiber: 2g Sugar: 31g
Nutrition information is automatically calculated by Spoonacular. I am not a nutritionist and cannot guarantee accuracy. If your health depends on nutrition information, please calculate again with your own favorite calculator.
Did you make this recipe?Please leave a comment below. And share a photo on Instagram with the hashtag #afarmgirlsdabbles or tag @farmgirlsdabble!
This post was originally published in 2012, then updated in 2025.
I love buttersctoch. Like LOVE IT. This recipe sounds amazing!!!
Yumm-o!! I could go for some of these tonight!
So homey and inviting, yum!
I think I could eat the whole pan of these bars! I love butterscotch and with chocolate and marshmallows?? What a combination!
Mmm, butterscotch. That’s all I needed to hear.
These are so fun! Love the melty marshmallows!
Treats from childhood are so fun to bake and bring a wonderful sense of comfort. Mom’s baking recipes are unparalleled! The butterscotch bars look tasty and the textures looks just perfect for my chewy, crispy sweet tooth.
This recipe arrived at just the right time for this Kansas farm wife. I was looking to make a bar cookie to take to the guys working on planting the 2013 wheat crop. They are currently cooling on the kitchen counter, and I couldn’t resist trying a corner before it was cool. Yum! Thanks for sharing in time for the guys’ supper!
Yay! LOVE to hear this, thanks!! :)
Usually butterscotch overpowers anything that it’s in, at least for me, but I do love the flavor.
I like the idea is disappearing marshmallows :) I like when marshmallows are so soft and gooey and then you take a bite of one and it stretches out. That’s the best :)
These sound so tasty! Love this idea :)
Your mom’s recipe is a keeper! Love the *disappearing* marshmallows.
I love your blog. It is beautiful! I love these too :) I will have to try them very soon! Thanks so much for such a wonderful recipe!
Thank you so much, Bobbie – so nice to meet you!
I have made these bars many times and I love them! The “pockets of ooey gooey chewiness” are the best. Perfect! Love your blog.
“Disappearing marshmallows-” that’s what caught my attention. I’m intrigued. :)
The marshmallows are so fun, Brenda! I love butterscotch, too!
So Fall-ish…I love it!! Love the disappearing marshmallows tagline!!
My family would love these bars! I need to go get some butterscotch chips though. These will go over big I am sure!
What luscious looking bars!
i need these.
like
right now
what is the baking time for an 8-inch square pan? i don’t trust myself with a 9 x 13 of these
Hi Natalie – For an 8″ pan, half the ingredients. I’m guessing about 20 minutes, but set your timer a little sooner than that to check on the doneness.
I love making bar treats and these look fabulous!