Mint chocolate brownies with cookie crust layer a crisp chocolate-crumb base under a dense, fudgy brownie, cool mint buttercream, and a thin dark chocolate ganache. They have the refreshing flavor of a classic mint-chocolate treat with the richness of a homemade brownie, and each square stays neat enough for a dessert platter.
The recipe takes about 1 hour of active work, plus cooling time before frosting and slicing. Bake it in a 9-by-13-inch pan for 16 generous squares. The cookie crust is pressed into the pan and briefly baked before the brownie batter goes on top, which helps it stay crisp beneath the fudgy layer.
Why You’ll Love These Mint Chocolate Brownies with Cookie Crust
The three layers give every bite a little contrast: buttery chocolate cookies, soft brownie, and cool peppermint frosting. A simple ganache goes over the top in a thin layer, so the mint does not become too sweet or heavy. You can make the brownies a day ahead and cut them once the topping has set.
- Big dessert-shop flavor: Chocolate, mint, and ganache make a familiar combination with a homemade finish.
- Fudgy center: A modest amount of flour keeps the brownie layer dense and moist.
- Clean layers: Cooling each layer before adding the next keeps the frosting from melting.
- Easy to portion: Chill the pan briefly and use a warm knife for tidy squares.
Ingredients You’ll Need
For the cookie crust
- 24 chocolate sandwich cookies, filling included
- 4 tablespoons unsalted butter, melted
For the brownie layer
- 10 tablespoons unsalted butter
- 1 cup granulated sugar
- 2 large eggs, at room temperature
- 1 teaspoon vanilla extract
- ¾ cup unsweetened cocoa powder
- ½ cup all-purpose flour
- ¼ teaspoon fine salt
- ½ cup semisweet chocolate chips
For the mint buttercream and ganache
- 4 tablespoons unsalted butter, softened
- 1½ cups powdered sugar
- 1 to 2 tablespoons heavy cream or milk
- ¼ teaspoon peppermint extract, plus more only if needed
- 2 drops green gel food coloring, optional
- 4 ounces semisweet or dark chocolate, finely chopped
- â…“ cup heavy cream
Peppermint extract is concentrated, so begin with ¼ teaspoon and taste before adding more. Mint extract varies by brand; a light, cool flavor is easier to build than to correct if the frosting becomes too strong.
How to Make Mint Chocolate Brownies with Cookie Crust
- Prepare the pan. Heat the oven to 350°F. Line a 9-by-13-inch baking pan with parchment, leaving enough overhang to lift the brownies out later. Lightly coat the parchment with nonstick spray.
- Make the crust. Pulse the sandwich cookies in a food processor until finely crushed, or place them in a sealed bag and crush them with a rolling pin. Stir in the melted butter until the crumbs look evenly moistened. Press firmly into the bottom of the pan.
- Par-bake the crust. Bake the crust for 8 minutes, then place the pan on a rack while you mix the brownie batter. Keep the oven on.
- Melt the brownie butter. Melt the 10 tablespoons of butter in a saucepan or microwave-safe bowl. Whisk in the sugar while the butter is warm. Let it cool for 3 to 4 minutes so it is warm, not hot.
- Build the batter. Whisk the eggs and vanilla into the butter mixture until smooth. Sift or whisk together the cocoa powder, flour, and salt, then fold them into the wet ingredients just until no dry streaks remain. Fold in the chocolate chips.
- Bake the brownie layer. Spread the batter evenly over the warm cookie crust. Bake for 22 to 26 minutes, until the edges look set and a toothpick inserted near the center comes out with a few moist crumbs. Cool completely in the pan, about 1½ hours.
- Whip the mint frosting. Beat the softened butter until creamy. Add the powdered sugar in two additions, mixing on low. Beat in 1 tablespoon cream, the peppermint extract, and optional green coloring. Add more cream a teaspoon at a time until the frosting spreads easily. Taste and adjust the mint gently.
- Frost and chill. Spread the mint buttercream over the cooled brownie. Refrigerate the pan for 20 minutes to firm the frosting before adding the ganache.
- Make the ganache. Place the chopped chocolate in a heatproof bowl. Warm the heavy cream until steaming at the edges, then pour it over the chocolate. Let stand for 2 minutes and stir slowly until smooth. Cool for 5 minutes, then spread or drizzle it over the frosting.
- Set and slice. Refrigerate for 30 to 45 minutes, until the ganache is set. Lift the slab out by the parchment and cut into 16 squares with a sharp knife, wiping the blade between cuts.
For a thicker ganache cap, let the first layer set and add another drizzle. If the brownies are cold when sliced, let them stand for 10 minutes so the bottom crust does not crack under the knife.
Tips and Variations
Keep the brownie layer fudgy
Do not wait for a toothpick to come out completely clean; that usually means the center has baked too long. The brownie will continue to set as it cools. If your oven runs hot, begin checking at 20 minutes, especially near the edges.
Use a light hand with mint
Mint chocolate brownies with cookie crust taste best when peppermint is present but not medicinal. Use the exact extract listed, then add only a drop more at a time. If your extract is very strong, start with half the amount and taste the frosting.
Make it your own
- Chocolate cookie swap: Use chocolate graham crackers or chocolate wafers instead of sandwich cookies; add 2 tablespoons sugar to the crust if the wafers are unsweetened.
- White chocolate: Stir â…“ cup mini white chocolate chips into the brownie batter.
- Holiday finish: Sprinkle crushed peppermint candies over the ganache while it is still soft.
- Natural color: Leave out the food coloring; the mint flavor and layers stand on their own.
If you want a simpler base to compare, bake the site’s classic fudgy brownies without the crust. For another layered chocolate dessert, try chocolate mousse brownies or a scoopable brownie trifle. The peppermint brownie bread is another festive option when you want mint with a softer, sliceable crumb.
Storage and Serving
Store the brownies in a covered container in the refrigerator for up to 5 days. For the neatest serving, let them stand at room temperature for about 15 minutes before slicing or eating. Refrigerate leftovers within 2 hours; see FoodSafety.gov’s safe chilling guidance.
To freeze, chill the brownies until the ganache is firm, then cut into squares and wrap each one before placing them in a freezer-safe container. Freeze for up to 2 months. Thaw overnight in the refrigerator or for about 30 minutes at room temperature. Avoid warming them in the microwave, which can melt the mint layer unevenly.
Frequently Asked Questions
Can I make mint chocolate brownies with cookie crust a day ahead?
Yes. Assemble the full pan and refrigerate it overnight once the ganache has set. Cut the brownies the next day with a warm, dry knife. You can also bake and cool the base a day ahead, then frost and top it when you have time.
Can I use mint extract instead of peppermint extract?
Yes, but mint extract can include a blend of spearmint and peppermint and may taste sweeter or more herbal. Start with a small amount, taste the frosting, and adjust slowly.
How do I get clean brownie slices?
Chill the pan until the ganache is firm, lift the brownies out by the parchment, and use a sharp knife warmed under hot water and dried well. Wipe the blade between cuts to keep the green frosting from streaking across the chocolate topping.
Can I leave out the cookie crust?
Yes. Line the pan with parchment and bake only the brownie batter. Begin checking around 20 minutes because the thinner layer may finish sooner. The mint buttercream and ganache can stay the same.
Is it safe to taste the brownie batter?
No. Raw flour and eggs can carry harmful germs, so wait until the brownies are baked. The FDA explains why raw dough and batter are not safe to eat.
