Add onions and sugar. Saute over low heat for 15-20 minutes, stirring often to prevent scorching. Onions will become golden brown.
Sprinkle flour over onions and cook 2 minute, stirring constantly.
Add stock, stirring well to absorb the flour, wine, salt and pepper. Simmer for 10 minutes. Recheck seasoning. *****Soup can be made to this point 2 days in advance and left in refrigerator.
Broil bread slices on both sides until lightly browned.
Spoon hot soup into individual oven-bowls. Place a slice of Swiss or gruyere cheese in each bowl.
Top with bread.
Mix Parmesan cheese and the grated cheese. Sprinkle a thick layer of this cheese over each serving.
Drizzle the melted butter over top of each bowl.
Broil until cheese melts and starts to brown. Serve very hot.
Notes
*****Serves 8.
Recipe by Geaux Ask Alice! at https://geauxaskalice.com/french-onion-soup/