Bring a large pot of salted water to a boil and cook pasta until al dente according to package instructions.
Reserve ½ cup of pasta water, then drain pasta and set aside.
Heat olive oil in a large skillet over medium-high heat and cook smoked sausage slices until browned and crispy, about 4–5 minutes.
Remove sausage from the skillet and set aside.
In the same skillet, melt butter over medium heat and sauté minced garlic until fragrant, about 30 seconds.
Add heavy cream and milk (if using), then stir in Parmesan cheese, paprika, and Italian seasoning.
Simmer the sauce gently for 3–5 minutes until smooth and slightly thickened.
Return the cooked pasta and sausage to the skillet and toss to coat evenly with the creamy sauce.
Add reserved pasta water gradually if the sauce is too thick.
Season with salt, black pepper, and optional red pepper flakes to taste.
Serve hot, garnished with fresh parsley or basil and extra Parmesan cheese.