Preheat the oven to 350 degrees F and line a small baking pan with parchment paper. This size works for four brownies.
Melt the butter in a mixing bowl. Stir in the sugar until combined, then add the egg and mint extract and mix well.
Add the cocoa powder, flour, and salt to the bowl. Stir until the batter is smooth and no dry streaks remain.
Fold in the chocolate chips. Spread the batter evenly in the prepared pan.
Bake for 18 to 20 minutes until the center is set. Let the brownies cool completely in the pan.
Melt the dark chocolate melting wafers in a microwave-safe bowl in 30-second bursts, stirring between each. Dip the open end of each sugar cone into the melted chocolate and let the excess drip off. Place the cones on parchment to set.
Cut the cooled brownies into four squares. Place one dipped cone on top of each square to form the witch hat.