In a large dutch oven over medium-low heat, add butter and sliced mushrooms. Stir to coat mushrooms in butter then allow to cook untouched for 10 minutes. Stir well, then allow to cook for an additional 5 minutes untouched. Stir, cook another 5 minutes, mushrooms should be releasing their liquid. Continue cooking, stirring every 5 minutes until the mushrooms are tender and have released most of their liquid.
Add in minced garlic, bay leaf, fresh thyme, salt, and pepper. Cook for an additional minute, then add in wine and Worcestershire sauce. Allow to simmer gently until the wine has absorbed. Remove bay leaf and thyme sprigs, discard.
Dust mixture with flour and cook slowly for 5-7 minutes. Then add beef broth and simmer 10 minutes.