These 'Boo-nies' brownies from a New Orleans pastry chef hide surprise candy treats

New Orleans pastry chef Treybert Rintala provided this recipe for these adorable ghost-topped brownies.
In his hometown, Rintala offers a free Friday meal popup for food-insecure New Orleanians. Learn more about his efforts here.
These brownies are decadent with chocolate and have a surprise: there are marshmallows, candy corn, M&Ms and more hidden inside.
Ingredients
1/2 cup (1 stick) butter, cut into cubes, plus more for pan
1 1/4 cup semisweet chocolate chips
3/4 cup granulated sugar
3/4 cup brown sugar, packed
3 large eggs
1/4 cup unsweetened cocoa powder
1/2 teaspoon kosher salt
1 cup all-purpose flour
5 chopped Reese’s Peanut Butter Cups
1/2 cup M&Ms
1/2 cup candy corn
16 large marshmallows
1 1/2 cup white chocolate chips
3 tablespoons coconut oil
Black decorating gel
Instructions
Make brownies:
Preheat oven to 350°F. Brush a 9x9-inch baking pan with butter and line with parchment paper, leaving an overhang on two sides. Butter the parchment paper.
Set a large heatproof bowl over a saucepan of simmering water. Add to the bowl a 1/2 cup of the butter and the chocolate chips and melt, stirring until smooth. Remove bowl from heat and whisk in sugars. Whisk in eggs, one at a time, until fully combined.
Whisk in cocoa powder and salt, then fold in flour, chopped Reese’s, M&M’s and candy corn. Pour batter into baking pan.
Bake until a toothpick inserted in center comes out with moist crumbs, 35 minutes. Let cool completely.
Make ghosts:
Use the overhanging parchment paper to lift brownies out of pan, then cut into 16 squares. Arrange squares on a parchment-paper-lined rimmed baking sheet. Top each square with a marshmallow.
In a medium heatproof bowl, microwave white chocolate chips with coconut oil until melted. Stir until smooth.
Drizzle chocolate over each marshmallow-topped brownie. Refrigerate until set, about 10 minutes.
Use black decorating gel to create eyes and a mouth on each marshmallow.