Begin by melting 1 cup of unsalted butter in a medium saucepan over low heat. Allow to cool slightly, then combine with 2 cups of granulated sugar in a large mixing bowl.

Crack in 4 large eggs, one at a time, mixing thoroughly after each addition. Add 2 teaspoons of vanilla extract and blend.

In a separate bowl, whisk together 1 cup all-purpose flour, 1 cup cocoa powder, 1 teaspoon salt, and 1 teaspoon baking powder. Gradually fold this dry mixture into the wet ingredients.

Preheat your oven to 350°F (175°C) and prepare a 9×13 inch baking pan. Pour the batter into the pan and bake for 25-30 minutes.

Remove from oven and let cool on a wire rack for about an hour.

Melt some chocolate in a microwave-safe bowl. Dip the tops of ice cream cones into the melted chocolate, then roll in Halloween-themed sprinkles. Let the chocolate harden.

In a mixing bowl, combine 2 cups powdered sugar, 1/4 cup milk, 1 teaspoon vanilla extract, and green food coloring. Whisk until smooth and creamy.

Spread the green frosting over the cooled brownies and place the chocolate-dipped cones upside down on top to create the witch hats.