French Onion Soup - cooking recipe

Ingredients

1/4 c. butter or margarine
4 c. thinly sliced onions
4 (10 1/2 oz.) cans condensed beef broth, undiluted
4 to 6 slices French bread (1-inch thick)
1/4 c. grated Gruyere cheese
2 Tbsp. Parmesan cheese

Preparation

You may use any cheese of your taste.