Preheat your oven to 375°F (190°C).

In a large pot, bring salted water to a boil over high heat. Add elbow macaroni and cook until just al dente, about 6-8 minutes. Once done, drain the macaroni.

In a medium saucepan, melt 4 tablespoons of butter over medium heat. Whisk in 1/4 cup of all-purpose flour, stirring constantly for about 2 minutes to form a roux.

Gradually pour in 2 cups of whole milk while whisking continuously to avoid lumps. Cook until it thickens slightly, about 5-7 minutes.

Remove from heat, stir in 2 cups of shredded cheddar cheese and 1/2 cup of grated Parmesan until melted. Season with salt and pepper to taste.

Gently fold the cooked elbow macaroni into the cheese sauce until evenly coated.

Spoon the macaroni and cheese mixture into a generously buttered casserole dish.

Using a ghost-shaped cookie cutter, cut out shapes from the mozzarella and place them on top of the macaroni.

Sprinkle sesame seeds or peppercorns on the mozzarella ghosts.

Bake for 20-25 minutes, or until the cheese is bubbly and golden.

Allow to cool slightly before serving. Enjoy your spooky creation!