Preheat your oven to 350°F (175°C) to ensure it’s hot and ready for baking.
In a large mixing bowl, whisk together the flour, cocoa powder, baking soda, and salt.
In another bowl, cream together the softened unsalted butter, brown sugar, and white sugar until light and fluffy.
Add the egg and vanilla extract to the butter mixture and beat until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Grease your muffin tin lightly. Drop about 1 tablespoon of dough into each muffin cup and press to form a cup shape.
Bake for about 10-12 minutes, or until the edges are firm. Allow to cool for 5 minutes before transferring to a wire rack.
In a separate bowl, beat together the softened butter and powdered sugar until creamy. Add milk, mint extract, and food coloring, mixing until smooth.
Fill each cooled cookie cup with the mint filling using a piping bag or spoon.
Top each filled cookie cup with an Andes mint chocolate and let it melt slightly.
