Melt 1 cup of unsalted butter in a medium saucepan over low heat until fully melted, then remove from heat and cool slightly.

In a large mixing bowl, combine melted butter with 2 cups of granulated sugar, then add 4 large eggs one at a time, mixing thoroughly after each.

In a separate bowl, whisk together 1 cup of all-purpose flour, 1/2 cup of cocoa powder, 1/2 teaspoon of salt, and 1 teaspoon of baking powder; gradually add to the wet mixture.

Preheat the oven to 350°F (175°C), grease or line a 9×13-inch baking pan, pour in batter, and bake for 25-30 minutes.

Prepare chocolate ice cream cones and optionally dip in melted chocolate and sprinkles; set aside.

Whisk together 2 cups of powdered sugar, 2-3 tablespoons of milk, and food coloring until smooth; spread over cooled brownies.

Press each decorated cone into the center of each frosted brownie to resemble witch hats; add extra sprinkles.