2 onions, sliced in rings
1 tablespoon butter
1 tablespoon olive oil
4 cups beef stock (homemade or prepared, high quality beef soup base)
4 slices stale bread (preferably French or Italian)
4 slices provolone cheese or 4 slices swiss cheese
Heat olive oil and butter together in a pan large enough to hold the onions and broth. Saute onions very gently in half olive oil and half butter until soft and golden but do not allow them to brown. Pour beef stock into the pan with the onions and simmer gently for 1/2 an hour. Season to taste with salt and pepper. Divide into oven-proof bowls. Float the stale bread on top. Cover with the cheese and broil until the cheese bubbles and browns.