Cut onions. Cut ends off onions, slice in half. Place large flat end down. Slice onions into strips. Keep the strips 1/4 inch wide or wide so that they aren't too thin when they cook down.
Caramelize onions. Melt butter in dutch oven or large stock pot over medium heat. Add onions. Stir to coat onions with butter. Stir every 5 minutes until onions become translucent, then blonde. Stir every 1-3 minutes as onions become a rich caramel color. Add splash of wine if onions begin to stick. This whole process usually takes 45 minutes - 1 hour. Stir in garlic. Add flour. Stir to coat onions.
Deglaze pan & add seasonings. Add wine. While steaming, remove the browned bits from the bottom of the pan. When pan is deglazed, add broth, Worcestershire, herbs & seasonings. Add only a portion of the salt you think you will need.
Simmer. Let soup simmer for 30- 45 minutes. Taste. Add extra salt if needed.
Toast the bread. When soup is nearing the end of its simmer, slice baguette and brush with olive oil. Toast in oven.
Broil the topping. When soup is ready, place oven safe crocks or ramekins on a baking sheet. Ladle soup into the crocks. Top with 1-2 Tbsp grated Provolone cheese. Place toasted baguette slices on top of cheese. Then top baguette with about 1/4 C more cheese. Place under broiler in oven until cheese is golden and melted and soup is bubbly.