Bring a large pot of salted water to a boil and cook the pasta until al dente according to package directions.
Reserve half a cup of pasta water, then drain and set pasta aside.
Heat olive oil in a large skillet over medium-high heat and cook sliced sausage until browned and slightly crispy, about 4–5 minutes.
Remove sausage from skillet and set aside.
In the same skillet, melt butter over medium heat and sauté minced garlic for 30 seconds until fragrant.
Add heavy cream and optional milk, stirring in Parmesan cheese, paprika, and Italian seasoning.
Simmer sauce gently for 3–5 minutes until smooth and slightly thickened.
Return cooked pasta and sausage to skillet and toss to coat in the creamy sauce.
Add reserved pasta water gradually to loosen sauce if needed; season with salt, pepper, and optional red pepper flakes.
Serve hot, garnished with fresh parsley or basil and extra Parmesan cheese if desired.