Melt butter in a large Dutch oven over medium-low heat; add onion. Cover and cook 30 minutes or until dark brown, stirring occasionally. Add wine and apple juice; bring to a boil. Boil, uncovered, 10 minutes or until liquid is reduced to about 1/2 cup. Stir in broth and consommé; bring to a boil. Reduce heat, and simmer, uncovered, 15 minutes.
Arrange bread slices on a large baking sheet. Broil 1 minute on each side or until golden.
Place 6 (2-cup) ovenproof bowls or soup crocks on a large baking sheet. Spoon soup into bowls. Top each bowl of soup with 2 slices toasted French bread, 1 1/2 tablespoons cheese, and 1 teaspoon parsley. Broil 2 to 3 minutes or just until cheese melts.