Peel and slice the onions then heat the butter in a large saucepan adding a little of the sugar. Cook very slowly and keep stirring until they are golden brown. Then add the stock, sugar and simmer for about an hour with a lid on.
When it is ready add the cognac and salt and pepper. Add a slice of bread covered with cheese on top on each bowl of soup and grill till melted.
4 medium onions
4 tblsp butter
1 tsp sugar
2 1/2 pints of stock
4 tblsp cognac
4 oz gruyere cheese
4 slices of French bread stick
