If you're not a fan of spicy food, reduce the amount of red pepper flakes in the recipe.
To make this recipe vegetarian, omit the ground beef or sausage and add extra vegetables to the sauce such as mushrooms, spinach, bell peppers, etc.
For an even cheesier dish, sprinkle some Parmesan cheese over the top before baking.
For a crunchy topping, add some panko bread crumbs and/or shredded cheese over the top of the dish before baking.
If your cream cheese has been in the refrigerator for too long and won't melt easily, try heating it in the microwave first so you can stir it into the sauce more easily.
For an extra creamy dish, stir in some ricotta cheese before baking.
If you don't have an oven-safe skillet, transfer the pasta to a casserole dish before adding the mozzarella cheese.