Preheat the oven to 400 degrees F.
Line a baking sheet with parchment paper. Sprinkle the cheese onto the parchment in a thin layer in the shape of the dish you will be serving the mac and cheese in.
Bake until the cheese is completely melted and evenly browned, 8 to 10 minutes. Let cool completely. Carefully remove the baked cheese from the parchment and place on top of the mac and cheese in the serving dish.