Preheat your oven to 350°F (175°C).

Bring a pot of salted water to a boil, add elbow macaroni, and cook until al dente, about 6–8 minutes. Drain and set aside.

Melt 4 tablespoons of unsalted butter in a medium saucepan over medium heat, whisk in 4 tablespoons of all-purpose flour, and cook for 2 minutes.

Gradually whisk in 4 cups of whole milk and stir for 5–7 minutes until thickened. Add garlic powder, onion powder, mustard powder, and season with salt and pepper.

Reduce heat to low, stir in cheddar, Gruyère, and mozzarella cheeses until melted and smooth.

Combine drained macaroni with cheese sauce until well-coated.

Mix panko breadcrumbs, grated Parmesan cheese, and melted butter for the topping.

Pour macaroni and cheese mixture into a greased 9x13-inch baking dish and top with breadcrumbs.

Bake for 25–30 minutes or until golden brown and bubbling.

Garnish with parsley before serving.