• Preheat oven to 350°F and grease 8x8 pan. You can also line with parchment paper.
• Beat together the unsalted butter, granulated sugar, and vanilla until smooth.
• Beat in the eggs one at a time.
• In a separate bowl, mix together the flour, baking powder, cocoa powder, and salt.
• Beat together the dry ingredients into the wet ingredients.
• Stir in the crushed chocolate mint cookies.
• Spread the batter into the prepared pan, paying attention to spreading it evenly.
• Bake for 35 to 40 minutes. Check the center with a toothpick to check for doneness.
• Remove from oven and cool completely on a wire rack before icing.

Brownie Icing

• Beat together the softened butter and the confectioner's sugar together.
• Add in the cocoa powder, blending well.
• Beat in the vanilla extract.
• Add in the milk a little at a time. Add more milk if needed to reach the desired consistency.
• Frost the cool brownies and add the crushed chocolate mint cookies on top.
• Cut into 9 squares and store in an air tight container.