In a large Dutch oven, combine onion, butter, salt, and pepper over medium-high heat. Cook, stirring frequently, until dark golden brown, 50 to 60 minutes. Increase heat to high. Add wine; cook until most of liquid has evaporated. Stir in broth.
Tie together thyme sprigs and bay leaves with kitchen twine. Add to broth mixture; bring to a boil. Reduce heat to medium; cook, uncovered, until slightly thickened, about 30 minutes. Remove thyme sprigs and bay leaves before serving. Garnish with cheese and thyme, if desired.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/our-favorite-fall-soup-bread-pairings/