In a 12-inch skillet heat butter and olive oil over medium heat until butter melts. Add onions, salt, and pepper. Cook, covered, for 15 minutes, stirring occasionally. Uncover. Cook for 10 to 15 minutes more or until onions are tender and browned, stirring frequently. Remove onions from skillet; set aside.
Add pasta to hot skillet. Cook and stir for 4 minutes or until pasta is browned. Add cooked onions and water to skillet. Bring to boiling; reduce heat. Cover and cook 5 minutes. Uncover. Cook for 3 to 4 minutes more or until pasta is tender, stirring occasionally. Serve immediately. Makes 4 (3/4-cup) servings.