In a large pot or deep skillet, combine the uncooked penne pasta, water, whole milk, minced garlic, salt, black pepper, and dried Italian seasoning.
Place the pot over medium-high heat and bring the mixture to a boil, stirring occasionally to prevent the pasta from sticking.
Once boiling, reduce the heat to medium and simmer uncovered, stirring frequently, until the pasta is tender and most of the liquid is absorbed, about 12 to 15 minutes.
Remove the pot from heat and stir in the unsalted butter until melted.
Add the shredded sharp cheddar cheese, shredded mozzarella cheese, and grated Parmesan cheese to the pasta. Stir until all the cheese is melted and the sauce is creamy and smooth.
Taste and adjust seasoning with additional salt and pepper if desired.
Serve immediately, garnished with extra Parmesan cheese if preferred.