6 tbsp. butter
6 lg. Spanish yellow onions, sliced
6 slices of thick French bread
1/2 lb. Gruyere of Swiss cheese, grated
2 qt. beef stock or 6 (10 1/2 oz.) cans beef broth
6 egg yolks, lightly beaten

Melt butter in large saucepan. Cook onions over lowest heat until limp but not brown. Add beef stock, simmer 15 minutes over medium heat. Puree hot soup in batches in blender. Combine egg yolks. Place one slice bread in each soup bowl. Pour in soup. Cover with cheese; place under preheated boiler for a minute or so to melt butter and slightly brown it.