In a large pot, bring salted water to a rolling boil over high heat. Add the elbow macaroni and cook for about 6–8 minutes until just tender but still al dente. Once cooked, drain the pasta and set it aside in the pot to keep it warm.

In a medium saucepan over medium heat, melt 4 tablespoons of butter until bubbly. Whisk in 4 tablespoons of flour and cook for about 1 minute to form a smooth paste.

Slowly pour in 3 cups of milk, whisking continuously to eliminate lumps, and increase the heat to medium-high. Continue cooking and stirring for about 3–4 minutes until the mixture thickens.

Once the sauce has thickened, reduce the heat to low and stir in 2 cups of shredded cheddar and ½ cup of grated Parmesan cheese until melted. Season with salt and pepper to taste.

Add the drained macaroni back into your cheese sauce, ensuring every piece is well-coated. Stir until fully combined.

Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish using olive oil or butter. Pour the mac and cheese mixture into the dish.

Place the ghost-shaped mozzarella slices on top of the mac and cheese, pressing them gently into the mixture.

Sprinkle black sesame seeds or peppercorns on the mozzarella for ghostly eyes if desired.

Bake uncovered for 20–25 minutes until the cheese is bubbly and the top is golden brown.

Let the dish cool slightly for about 5 minutes before serving warm.