Cheesy Macaroni and Cheese

Cook pasta according to package directions, drain, set aside. In medium sauce pan sauté onion in butter until transparent. Add flour and pepper, cook for 1-2 minutes until flour is cooked. Add milk. Cook until bubbly and slightly thickened. Add cheese and stir until cheese is melted. Combine cheese sauce with cooked pasta. Heat in large pot for additional 5-10 minutes to heat through.