Preheat the oven to 350°F (175°C). Line a baking pan with parchment paper to prevent sticking.
In a large mixing bowl, combine melted butter and granulated sugar, whisking until smooth and glossy.
Add eggs, one at a time, whisking well after each addition to incorporate air and create a smooth batter.
Stir in vanilla extract for aroma and flavor.
Sift together cocoa powder, flour, baking powder, and salt; gradually fold into the wet mixture until just combined. Be gentle to keep the batter light.
Mix in chocolate chips for bursts of chocolate flavor throughout the brownies.
Pour the batter into the prepared baking pan, spreading evenly with a spatula.
Bake for 25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Cool completely on a wire rack.
Once cooled, use a round cutter or freehand to cut the brownies into ghost shapes—ovals or rounded tops work well.
Prepare the icing by mixing powdered sugar with milk until smooth and drizzle consistency. Divide and add food coloring as desired for eyes and mouths.
Use a piping bag or plastic squeeze bag to decorate each ghost with eyes and a mouth, creating a spooky expression.
Arrange the decorated ghost brownies on a serving platter and enjoy their spooky, fudgy appeal.
