Marshmallow Brownies

Marshmallow Brownies are a great way to upgrade your store-bought brownies and make them look fancy.

With a baby who wants to be held all the time, it’s hard to make fancy stuff. This summer we’ve been more and more busy getting involved in lots of things. Sometimes you want to bring a fancy treat to the barbecue but you don’t have the bandwidth to make it from scratch. Here is an easy way to make those Ghirardelli brownies from Costco a little more fancy.

Marshmallow Brownies

Ingredients

1 box brownie batter powder
1 egg
1/3 cup milk
1/3 cup vegetable oil
3 1/2 cups mini marshmallows
1/2 cup chocolate chips

Marshmallow Brownies

Directions

Prepare two pans: the first pan will be an 8×8 inch square baking pan. Line it with parchment paper, leaving some hanging over the sides. This makes it easier to remove the brownies later. Prepare a second pan, either a 8×4 loaf pan. Line it with parchment paper. Preheat the oven to 350°F.
Mix the brownie batter according to the directions. I switched out water for milk.
Add two thirds of the brownie batter into the prepared 8×8 pan. Pour the remaining one third of the batter into the loaf pan. Bake both pans of brownies at the same time for 27-36 minute. To know when they’re ready, insert a toothpick inserted in the middle of each pan – it should come out with a few wet crumbs on it when it’s ready.
Remove the pans from the oven, but leave the oven on. Set the loaf pan aside. Pour mini marshmallows evenly on top of the brownies in the larger square baking pan and put them back in the oven for another 4-8 minutes, or until the marshmallows look gooey and have started to turn a light golden brown. Meanwhile, use a spoon to break up the brownies in the loaf pan into chunks or small pieces. Careful, they will still be hot!
Remove the marshmallow brownies from the oven. Take small chunks of crumbled up brownie from the loaf pan and sprinkle over top of the marshmallow layer, gently pushing them into the marshmallows. Repeat with all the crumbled up brownie pieces, then evenly sprinkle with chocolate chips.
Let cool before removing from the pan and slicing.

Gooey Marshmallow Brownies

Calorie Count

The entire batch clocks in at roughly 5,200 calories. If you slice it into 24 squares, each brownie has about 220 calories.

Marshmallow Brownies

Nutritional Facts (per brownie)

Nutrient	Amount
Calories	220
Total Fat	8 g
Saturated Fat	4 g
Cholesterol	15 mg
Sodium	85 mg
Total Carbohydrates	30 g
Dietary Fiber	1 g
Sugars	20 g
Protein	2 g

Marshmallow Brownies

Cooking Tips

Preheat oven to 350 °F and line a 9×19-inch pan with parchment for mess-free removal.
Fold half the marshmallows into the batter—this keeps them pillowy and builds melty pockets.
After spreading batter, sprinkle the rest of the marshmallows and chocolate chips on top for a decadent crust.
Bake until a toothpick yields moist crumbs; any longer and marshmallows can toughen.
Let brownies cool fully before slicing to get clean edges while preserving gooey centers.

Marshmallow Brownies

Recipe Variations

Peanut Butter Swirl Dollop ¼ cup of softened peanut butter over batter and swirl with a knife.
Caramel Surprise Drop spoonful’s of caramel sauce between marshmallow clusters for gooey caramel bursts.
Nutty Crunch Stir in ½ cup chopped pecans or walnuts to the batter for texture.
Dark Chocolate Twist Swap milk chips for ½ cup bittersweet chocolate chips to deepen the flavor.
S’mores Style Top with crushed graham crackers and mini marshmallows, then broil 1–2 minutes for toasted peaks.

Marshmallow Brownies

Final Thoughts

This spin on boxed brownies transforms a simple weeknight bake into an indulgent, nostalgic treat. The clouds of marshmallow and melty chocolate chips punctuate each fudgy bite, making these squares perfect for potlucks, casual gatherings, or whenever you crave an easy show-stopper. Play with mix-ins, baking times, or pan sizes to tailor gooeyness and texture to your liking—every tweak unlocks a new level of brownie bliss.

Looking to store leftovers? Keep them in an airtight container at room temperature for up to 3 days—or pop individual squares in the freezer for a quick, comforting snack later on. Let us know if you try this recipe and tag us on Instagram!