Place the butter on the bottom of a large slow cooker. Place thyme and bay leaf in cheese cloth (or plan to dig them out later) in the cooker. Peel and slice the onions vertically into small slivers. Add the onions to the cooker. Sprinkle the onions with sugar. Cover and cook on high for 8 hours or until you get home from work in 8-10 hours. DO NOT ADD WATER Remove thyme and bay leaf; discard. Add in the beef consomme, water, Worcestershire sauce, red wine vinegar, pepper, and salt. Cover and let cook on high while you prepare your baguette. Slice bread into slices about 1 to 1 1/2 inch in width (1 if you have a bread bowl, 1 1/2 if you are using a ramekin). Place bread on a baking sheet and broil until browned on both sides (less than 1 min per side). Remove from oven. Pour soup into bread bowls, or oven safe soup ramekins and top with about 2 tbs of Gruyere cheese and top it all with a slice of Swiss cheese. Place bowls on a baking sheet and back the broiler until the cheese is melted and starting to bubble and brown a little (about 2-3 minutes). Enjoy!