These adorable Monster Bash Brownies are one of my favorite Halloween treats to make with family. They combine a rich, bakery-style brownie base with a marshmallow topper dipped in white chocolate ganache and decorated to look like playful monsters or spooky ghosts. They’re quick to assemble, easy to customize, and perfect for Halloween parties, classroom treats, or a festive family baking night.
It’s a Monster Bash! Make your monsters your own — change the color, change the decorations, and have fun!
Get creative with colors and decorations. In the photos you’ll see two versions: purple marshmallow monsters and white ghosts. You can color the ganache any shade you like with gel food coloring, add multiple candy eyes, use sprinkles, edible glitter, or piping gel for mouths and details. These are meant to be playful — there’s no wrong way to decorate them.
If you enjoy a chewy, fudgy brownie, this recipe yields a sturdy, bakery-style base that holds up well under the marshmallow and ganache. The recipe below is adapted from King Arthur Flour and produces a dense, slightly chewy brownie that’s ideal for stacking and decorating. If you prefer convenience, a boxed brownie mix works fine — aim for a thick batter by using a smaller pan (8×8 or 9×9) or by doubling the mix for a 9×13 pan so the brownies are tall enough to support the marshmallow and decorations.
Our favorite Halloween tradition and printable
One family tradition we love is “BOOing” neighbors or friends. You prepare two plates of treats — Monster Bash Brownies are perfect — print a little poem or note, and quietly leave the treats at two neighbors’ or friends’ doors. When someone is BOOed, they display the poem or note on their door or window so others know they’ve already been surprised. It’s a simple, fun activity that spreads festive cheer and gets everyone involved in the Halloween spirit.
How to make the ganache
White chocolate ganache is made by gently heating cream, pouring it over white chocolate chips, letting it sit briefly, then stirring until smooth. The ganache should be thin enough to pour and coat marshmallows but thick enough to set and hold decorations. If you color the ganache, use gel-based food coloring rather than water-based color, which can cause the chocolate to seize and become grainy.
How to substitute cream
If you don’t want to buy a full pint of cream for a small amount, use this simple substitution:
- 2 ½ tablespoons cream = 1 ¾ tablespoons milk + ½ tablespoon melted butter
Enjoy!
Alyssa
Check out these other fun Halloween treats
- Monster Halloween Cupcakes
- Spooky 5-minute Fudge
- Mummy Jalapeño Poppers
- Hocus Pocus Potion Float
Don’t forget to save this recipe for later and try different color and decoration variations. If you make these, snap a photo and share with friends and family to inspire others to get creative in the kitchen.
Monster Bash Brownies
Summary: Brownies topped with a marshmallow, coated in white chocolate ganache, then decorated as monsters or ghosts for a fun Halloween treat.
Author: Alyssa — In Fine Taste
Course: Brownies & Bars | Cuisine: American
Prep Time: 5 minutes | Cook Time: 25 minutes | Total Time: 30 minutes | Servings: 9
Ingredients
Brownies:
- 10 tablespoons Hershey’s Special Dark cocoa powder
- 2 large eggs
- 8 tablespoons butter
- ¾ cup white sugar
- 6 tablespoons packed brown sugar
- 1 teaspoon vanilla
- ½ teaspoon salt
- ½ teaspoon baking powder
- ¾ cup flour
- 1 cup semisweet chocolate chips
Monster decoration:
- 2 ½ tablespoons cream (or substitute: 1 ¾ tablespoons milk + ½ tablespoon melted butter)
- ½ cup + 2 tablespoons white chocolate chips
- Pinch of salt
- Gel food coloring (optional)
- 9 large marshmallows
- Candy eyes
- Black gel decorating icing
Instructions
- Preheat oven to 350°F (177°C). In a large bowl, whisk eggs and cocoa powder together and set aside.
- In a microwave-safe bowl, combine butter and both sugars. Microwave for 90 seconds, stirring every 30 seconds, until melted and combined. Let cool until warm but not hot.
- Slowly stir the egg and cocoa powder mixture into the butter and sugar mixture. Add baking powder, salt, vanilla, and flour. Stir until combined. Let the batter cool slightly, then stir in the semisweet chocolate chips.
- Line a 9×9-inch pan with foil and grease the foil. Spread batter evenly and bake for about 25 minutes. Remove and cool completely before decorating.
- To make the ganache: heat the cream for 30 seconds in the microwave, add the white chocolate chips, and let sit for 1 minute. Stir until smooth, microwaving in short 15-second bursts if needed. Stir in a pinch of salt and gel coloring if using.
- Cut cooled brownies into 9 equal squares. Add a small dab of ganache to the bottom of each marshmallow and press onto each brownie. Chill in the refrigerator for 5 minutes to set.
- Spoon a generous amount of ganache over each marshmallow, coaxing it down the sides so the marshmallow is fully coated and some ganache reaches the brownie. Add candy eyes while the ganache is still soft. Chill until the ganache is firm, then use black gel icing to draw mouths and other features.
- Serve chilled or at room temperature. Store leftovers in an airtight container in the refrigerator for best texture.
Nutrition (approximate per serving)
Calories: 540 kcal | Carbohydrates: 76 g | Protein: 6 g | Fat: 25 g | Saturated Fat: 15 g | Cholesterol: 75 mg | Sodium: 282 mg | Fiber: 3 g | Sugar: 51 g
If you try this recipe, please leave a review and share a photo — seeing your creative monster designs is the best part!
Share your photos on social media and tag #infinetasterecipes so we can see your Monster Bash Brownies. Enjoy baking and have a spooky, delicious Halloween!