Cook the Pasta: Boil spaghetti in salted water according to package instructions until al dente. Reserve ½ cup pasta water and drain.
Melt the Butter: In a large skillet over medium heat, melt butter and sauté garlic until fragrant (about 1 minute).
Make the Creamy Base: Add cream cheese and milk. Stir continuously until the cream cheese melts into a smooth sauce.
Add Cheese & Seasoning: Stir in Parmesan, salt, pepper, and Italian seasoning.
Combine Pasta: Add the cooked spaghetti and toss to coat. Add a splash of reserved pasta water if the sauce needs thinning.
Finish & Serve: Plate the pasta and top with extra Parmesan and parsley.