French Onion Soup - cooking recipe

Ingredients

3 c. thinly sliced/diced onions (preferably Spanish)
1/4 c. butter
1/2 tsp. salt (or to taste)
1/4 c. sugar
2 Tbsp. flour
1 qt. beef bouillon (stock)
8 slices French bread
8 slices Mozzarella cheese
1 c. grated Parmesan cheese

Preparation

Saute onions and butter in skillet about 15 minutes, covered. Uncover and add salt, sugar and flour.
Stir well.
Cook about 2 minutes over low heat.