Name: Frankenstein Brownies Recipe
Prep time: 15 min
Cook time: 30 min
Total time: 45 min
Cuisine: American
Ingredients: 1 box brownie mix; Eggs, oil, and water as called for on the brownie mix box; 1/2 cup butter (1 stick), softened; 2 1/2 cups powdered sugar; 2 tablespoons milk; 1 teaspoon peppermint extract; 5+ drops green food coloring; 1/2 cup chocolate chips; Candy eyes; Mini M&Ms; Pretzel sticks (broken in half)

Jump to Recipe· 3.8 from 4 reviews

I absolutely love sharing my Frankenstein Brownies Recipe with anyone who enjoys a fun twist on classic brownies. This dessert combines rich, fudgy brownies with a refreshing mint frosting and playful decorations that turn each bite into a little Halloween masterpiece. It’s one of my favorite recipes to make when I want to impress guests or brighten up a party table with something both whimsical and delicious.

Why You’ll Love This Frankenstein Brownies Recipe

What really excites me about this Frankenstein Brownies Recipe is how perfectly balanced the flavors are. The deep chocolatey richness of the brownies is beautifully complemented by a cool, creamy mint frosting that refreshes the palate and adds just the right amount of sweetness. Then, the decorative touches—the candy eyes, mini M&Ms, and pretzels—give each brownie its own personality, making the whole experience more than just dessert; it’s a conversation starter.

Another thing I love is how easy this recipe is to put together. Using a brownie mix means the base is super simple, freeing you to focus on the fun part: decorating! It doesn’t require any complicated techniques, and the assembly can actually be a great activity to do with family or friends. These brownies are perfect for Halloween parties, potlucks, or just a creative weeknight treat. They really stand out because of that playful design combined with a fresh minty flavor that you don’t get in your average brownie.

Ingredients You’ll Need

The image shows square brownies decorated to look like green Frankenstein faces. Each brownie has two white candy eyes with black dots, a small round candy nose in different colors like yellow and green, and a mouth and hair made of wavy dark brown icing. The green frosting layer is thick and smooth, covering the top of the dark brown brownie base. Small pretzel sticks stick out from the sides of each brownie, acting as Frankenstein’s bolts. The brownies are placed on a white marbled textured surface. photo taken with an iphone --ar 4:5 --v 7

All the ingredients for this Frankenstein Brownies Recipe are straightforward and easy to find, but each one plays an important role in building the flavor, texture, and festive look of the dessert.

Brownie mix: The rich, fudgy base that gives these treats their classic chocolate foundation.
Eggs, oil, and water: As called for on your brownie mix box to keep the brownies moist and tender.

Butter (1/2 cup, softened): Essential for a smooth, creamy frosting texture.
Powdered sugar (2 1/2 cups): Provides sweetness and helps achieve the classic frosting consistency.
Milk (2 tablespoons): Thins the frosting to a spreadable consistency without losing richness.

Peppermint extract (1 teaspoon): Adds that refreshing mint flavor that sets these brownies apart.
Green food coloring (5+ drops): Gives the frosting its signature creepy, fun Frankenstein vibe.
Chocolate chips (1/2 cup): For melting and decorating the face’s hair and mouth.

Candy eyes: To create those iconic Frankenstein monster eyes that bring these brownies to life.
Mini M&Ms: Perfect for the nose or other facial features to add color and fun.
Pretzel sticks: Broken into pieces, they mimic the bolts on Frankenstein’s neck for an authentic finishing touch.

Directions

Step 1: Preheat your oven according to the instructions on your brownie mix box. Prepare the brownie mix with eggs, oil, and water as directed, then pour the batter evenly into a greased 9×13-inch pan.

Step 2: Bake the brownies as the box suggests, usually around 25 to 30 minutes. Make sure to test for doneness by inserting a toothpick—it should come out with a few moist crumbs but not wet batter.

Step 3: Allow the brownies to cool completely in the pan to ensure the frosting doesn’t melt when spread on top.

Step 4: While the brownies cool, beat the softened butter in a medium bowl for about 2 minutes until smooth and creamy.

Step 5: Add powdered sugar, milk, peppermint extract, and green food coloring to the butter. Beat on high speed for 1 to 2 minutes until the frosting is light, fluffy, and spreadable. Adjust with a bit more powdered sugar or milk if needed.

Step 6: Spread the mint frosting evenly across the top of the cooled brownies. Let the frosting set for at least 20 minutes; this helps it firm up and makes the decorating easier.

Step 7: Cut the brownies into 15 to 18 pieces and carefully remove them from the pan.

Step 8: Melt the chocolate chips in the microwave for about 1 minute, stirring every 20 seconds until smooth and glossy.

Step 9: Transfer the melted chocolate into a ziplock bag, snip off a tiny corner, and drizzle over each brownie to create Frankenstein’s hair and mouth.

Step 10: Place two candy eyes and one mini M&M on each brownie piece to form the face, then insert two pretzel stick halves on the bottom sides of each brownie to mimic bolts.

Step 11: Stand back and admire your Frankensteins before enjoying them with friends and family!

Servings and Timing

This Frankenstein Brownies Recipe yields about 15 to 18 servings, depending on how large you cut the pieces. Prep time is approximately 15 minutes, mostly hands-on while mixing and decorating. The bake time is around 25 to 30 minutes using a boxed brownie mix. Adding in cooling time for the brownies and setting time for the frosting, you’ll want to account for about 1 hour total from start to delicious finish. The resting time is crucial—the frosting needs to firm up so your decorations don’t slide off!

How to Serve This Frankenstein Brownies Recipe

The image shows square brownies decorated like Frankenstein faces, each brownie is covered with a bright green layer of frosting as the base. On top, there is a thick dark brown layer representing hair with vertical lines for texture. White candy eyes with black dots are placed near the top center, and a single yellow candy is used as a nose in the middle. A dark brown frosting line forms a simple, slightly curved mouth with a small vertical stitch line on the right side. Pretzel sticks are placed on the sides as bolts. The brownies are arranged on a white marbled surface, and a woman's hand is in the top left corner, reaching for one. Photo taken with an iphone --ar 4:5 --v 7

I love serving these Frankenstein Brownies chilled or at room temperature because the mint frosting tastes so fresh and pleasant when cool. For a little extra indulgence, try warming one slightly for 10 seconds in the microwave—it softens the brownie and slightly melts the chocolate drizzle, which is heavenly, but be careful not to melt the frosting! I often plate 2 or 3 mini brownies per person on a black or green plate to really make those colors pop.

When it comes to garnishes, I sometimes sprinkle a few crushed peppermint candies around the plate or add a dollop of whipped cream on the side to complement the mint frosting. They look fantastic next to a scoop of vanilla ice cream, which makes the dessert feel even more special. For drinks, a cup of rich black coffee or hot cocoa pairs beautifully, and if you’re feeling festive, a minty cocktail or an herbaceous green tea can bring out the mint notes even more.

These brownies are a perfect fit for Halloween parties, autumn gatherings, or any time you want to surprise guests with something playful and delicious. Their unique design makes them a centerpiece, and their unmistakable flavor means they disappear fast. I love making a big batch to share and watching the smiles as people pick their favorite Frankenstein face from the platter.

Variations

One of the reasons I enjoy this Frankenstein Brownies Recipe so much is how adaptable it is. If you want to switch things up, you can swap in a gluten-free brownie mix to make these treats accessible to everyone at your table. For a vegan version, try using vegan brownie mixes and substitute the butter in the frosting with coconut oil or a plant-based spread—just keep the peppermint extract for that minty zing!

For flavor variations, I sometimes add a few drops of almond extract in the frosting along with peppermint for a little nuttiness. You can also experiment with different colored frostings—orange and purple make fun Halloween alternatives while still keeping the festive spirit alive. Another fun twist is to swap the pretzel “bolts” with small pieces of licorice or green gummy candy for a softer texture and a pop of bright color.

If you want to get really creative, you could bake the brownies in smaller muffin tins and then frost and decorate them individually for bite-sized Frankensteins. Or try making a layered Frankenstein-inspired dessert by stacking brownie squares with layers of mint mousse or pudding. The key is having fun with the look and flavor while keeping the mint-chocolate magic alive.

Storage and Reheating

Storing Leftovers

I recommend storing leftover Frankenstein Brownies in an airtight container at room temperature for up to 3 days. If your kitchen is warm, the refrigerator works fine; just remember that chilling might firm up the frosting, making the brownies a bit denser but still delicious. For best texture, allow refrigerated brownies to sit at room temperature for about 20 minutes before serving.

Freezing

These brownies freeze quite well, which is great if you want to make a batch ahead of time. Place them in a single layer on a baking sheet and freeze until firm to avoid sticking, then transfer to a freezer-safe container or heavy-duty ziplock bag. They can keep for up to 3 months. When you’re ready to enjoy, thaw them overnight in the refrigerator.

Reheating

When reheating leftover Frankenstein Brownies, I find it best to warm them gently in the microwave for about 10 seconds or less, just long enough to soften the brownie without melting the frosting completely. Avoid heating too long or at high power, as the frosting can become too runny. For a slightly warm but still firm frosting texture, letting the brownies come to room temperature after reheating works wonders.

FAQs

Can I make the frosting ahead of time?

Yes! You can prepare the peppermint frosting a day in advance and keep it covered tightly in the refrigerator. Just let it come to room temperature and give it a quick beat with your mixer before spreading to restore its fluffy texture.

What if I don’t have peppermint extract?

If you don’t have peppermint extract, you can substitute with vanilla extract for a classic taste, but you’ll lose the minty freshness. Another option is adding a small amount of crushed peppermint candies to the frosting for subtle flavor.

Can I use homemade brownies instead of a mix?

Absolutely! Homemade brownies work beautifully in this recipe and allow you to control the ingredients and texture. Just ensure they are fully cooled before frosting and decorating for the best results.

Are the candy decorations necessary?

They’re not required but they really bring the Frankenstein theme to life. You can use any candy you like or even make faces with nuts, raisins, or edible markers if you want a healthier or simpler look.

How do I keep the pretzel “bolts” from falling out?

inserting the small pretzel sticks gently but firmly into the sides near the bottom helps secure them. Waiting for the frosting to set before adding decorations also allows for a more stable surface.

Conclusion

I’m so thrilled to have shared my Frankenstein Brownies Recipe with you because it’s one of those desserts that brings joy not just in taste but also in creativity. It’s simple to make, wonderfully flavorful, and perfect for adding a bit of spooky fun to any occasion. I hope you’ll give it a try and enjoy the smiles these playful brownies bring as much as I do!