Preheat your oven to 350°F (175°C). Place parchment paper in an 8x8-inch baking pan to line it.

Melt the butter and dark chocolate chips together in a heatproof bowl over simmering water, stirring until smooth.

In another bowl, whisk the sugar and eggs (or flax eggs) together until well blended. Gradually add the melted chocolate mixture, whisking constantly as you pour.

Gently sift the flour, cocoa powder, baking powder, and salt into the bowl containing the wet ingredients, ensuring everything is well incorporated.

Gently fold the dry ingredients into the wet mixture, stirring until they are just combined.

Pour the batter into the prepared pan, spreading it evenly to form a smooth layer. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs attached. Let it cool completely.

In a mixing bowl, cream the softened butter until it becomes light and airy. Slowly incorporate the powdered sugar, continuing to blend until smooth and well combined. Stir in the peppermint extract and blend thoroughly until fully incorporated.

If the frosting is too thick, gradually add 1-2 tablespoons of plant-based milk to achieve a smoother texture.

Evenly spread the mint frosting across the cooled brownie layer. Place the mixture in the refrigerator for 20 minutes to allow it to firm up.

Place the dark chocolate chips and butter in a heatproof bowl. Melt them together over simmering water, stirring until fully smooth.

Pour the melted chocolate over the mint layer, then use a spatula to spread it evenly across the surface.

Let it set at room temperature or in the refrigerator before slicing.

Once the chocolate topping is set, slice the brownies into squares. Serve and enjoy!