In large Dutch oven over medium heat, melt butter. Add onions and sugar. Cover and cook, stirring occaisionally, 30 minutes or until onions are tender but not colored. Uncover pan, increase heat slightly and continue to cook, stirring regularly until onions are rich caramel colour (10 to 15 minutes) Do Not Let Onions Burn. Stir in flour until well blended. Gradually add wine; cook, stirring constantly, until mixture boils and thickens. Stir in beef broth and pepper; bring to boil. Reduce heat to low. Cover and simmer 15 minutes. Ladle soup into 6, 1-1/2 cup oven proof bowls. Top each with bread slice; sprinkle with swiss cheese and parmaean cheeses and paprika. Place bowls on jelly roll pan. Broil until cheese melts and bubbles.