Cook pasta according to package directions, just until al dente, and steam broccoli to desired tenderness, if using.

Melt the butter in a saucepan over medium heat.

Add the cream cheese and whisk until smooth.

Whisk in the milk gradually.

Mix in the parmesan, garlic powder, ground pepper, and nutmeg.

Add the mozzarella and continue to stir until it's completely melted.

Add salt and additional pepper to taste.

Remove from heat.

If sauce is too thick, thin with additional milk or some water.

Toss with al dente pasta and broccoli, if using.