Preheat the oven to 350 degrees F (175 degrees C). Line a 9x13-inch deep baking pan with parchment paper and set aside.
In a large bowl, use an electric mixer to cream together the vegan butter, granulated sugar, and brown sugar until light and fluffy.
Add the applesauce and vanilla extract. Mix until well combined.
In a separate bowl, whisk together the flour, baking powder, baking soda, and cocoa powder.
Add the dry ingredients to the wet mixture and mix until almost combined—some dry flour is okay.
Fold in the vegan chocolate chips and mix just until no dry flour remains. Do not over-mix.
Pour the batter into the prepared pan and spread evenly.
Bake for 40 to 45 minutes, or until a toothpick inserted in the center comes out mostly clean.
Remove from the oven and allow to cool completely on a wire rack for 3 to 4 hours. Do not frost until fully cooled.
In a large bowl, beat the vegan butter with an electric mixer until creamy.
Add ½ cup powdered sugar and 1 tablespoon plant-based milk. Mix well. Repeat until all sugar is added, adding more plant-based milk only if needed for spreadability.
Stir in the peppermint extract.
Optionally, add green food coloring ½ teaspoon at a time until the desired color is reached.
Spread the mint frosting evenly over the cooled brownies. Place in the refrigerator for 1 hour to set.
In a microwave-safe bowl, combine the vegan chocolate chips and 1 tablespoon of vegan butter. Microwave for 35 seconds, stir, then microwave again for 30 seconds. Stir and repeat as needed until fully melted—be careful not to burn the vegan chocolate.
Let the vegan chocolate cool slightly but remain pourable. Pour it over the frosted brownies and spread evenly.
Refrigerate for another hour to fully set the vegan chocolate layer.
Slice and serve!
Notes
Don’t over-mix: Mix batter just enough to combine the ingredients. Otherwise, you’ll get dense, tough brownies.
Cool before frosting: Otherwise, the frosting will melt right off.
Flavor with mint to taste: Too much can taste toothpaste-y. Start with a little and adjust to taste.
For clean cuts: Dip a sharp knife in hot water and wipe clean between slices. It’s tricky to get them perfect, but this definitely reduces mess.