In large pot of boiling water, cook pasta until tender. Drain well.
Meanwhile, in large nonstick skillet, heat oil over medium heat. Crumble in the sausage and cook until no longer pink. Add onion and garlic, stirring frequently, until onion is softened, about 7 minutes.
Stir spinach into skillet and cook until heated thoroughly. Add milk, cream cheese and pepper, stirring frequently, until slightly thickened.
Toss the sauce with the hot pasta and sprinkle Parmesan cheese over the top.