Melt butter in large skillet over medium heat. Add onions and cook, stirring occasionally, for 15 minutes or until onions are soft and translucent. Add minced garlic and cook another 60 seconds. Stir in wine, remove from heat and add to crock-pot.
Add chicken broth, salt and thyme to crock-pot and turn on low for 4-5 hours.
Ladle soup into bowls or ramekin and top with bread slice and cheese.