Cook the Pasta: Bring a large pot of salted water to a boil. Add penne and cook until al dente (about 10-12 minutes). Reserve ¼ cup of pasta water, then drain and set aside.
Sauté the Garlic: In a large skillet over medium heat, melt butter. Add minced garlic and sauté for about 30 seconds until fragrant.
Make the Creamy Sauce: Reduce heat to medium-low. Add heavy cream, milk, salt, black pepper, red pepper flakes (if using), and Italian seasoning. Stir well and let it simmer for 2-3 minutes.
Incorporate the Cheese: Gradually stir in the grated Parmesan, stirring continuously to prevent clumps. If the sauce is too thick, add reserved pasta water little by little until smooth.
Combine with Pasta: Add the drained penne pasta to the skillet and toss to coat evenly in the sauce. Let it cook for another 1-2 minutes to absorb the flavors.
Garnish and Serve: Remove from heat and top with fresh parsley, extra Parmesan, and a dash of black pepper. Serve immediately and enjoy!