1. In a microwaveable casserole, place the onions and butter or margarine.
2. Cover the casserole and place it in the microwave.
3. In the microwave, cook the onions on 100 per cent power or High for 6 to 8 minutes, till the onion is very tender, stirring once in between.
4. Take the casserole out of the microwave, and add the beef broth, Worcestershire sauce, and pepper
5. Mix everything well together.
6. Cover the casserole and place it back in the microwave.
7. In the microwave, cook the mixture on High for 4 to 6 minutes more, till it is heated through.
8. Serve sprinkled with croutons and shredded cheese.