Preheat your oven to 350°F (175°C) and grease a 9x9 inch baking pan. Substitute oil with melted butter in the brownie mix and combine until smooth.

Pour the brownie batter into the prepared pan and bake for about 25–30 minutes or until a toothpick comes out with a few moist crumbs. Allow to cool completely.

Once cool, lift the brownies out of the pan and cut into nine equal squares.

Spoon the vanilla frosting into a microwave-safe bowl and heat for about 10 seconds. Stir until smooth and spread on each brownie square.

Decorate the large marshmallows with fun ghost faces using the black writing gel.

Press one decorated marshmallow into the center of each frosted brownie.

Let the assembled brownies sit for about 10-15 minutes to ensure the frosting hardens slightly.