Melt 2 oz. of butter in a large sauté pan over medium-high heat until bubbling. Add sliced baby Bella mushrooms and allow them to brown without stirring for 5-7 minutes. Flip and cook for another 3-5 minutes. Remove from pan and set aside.

In the same pan, reduce heat to medium, add the remaining butter, sliced shallots, minced garlic, and fresh thyme. Sauté for 3-4 minutes until shallots are soft and fragrant.

Pour in red wine, beef broth, and Worcestershire sauce, stirring well. Increase heat to high, bring to a simmer and cook for about 10 minutes until the sauce thickens.

In a small bowl, create a slurry by mixing 2 tablespoons of flour with ¼ cup of beef broth. Gradually pour into the sauce while stirring continuously.

Season the sauce with salt and pepper to taste. Return sautéed mushrooms to the pan, stir to combine, and warm for a few minutes before serving.