Step 1

Melt 1 tablespoon of butter in a skillet over medium heat. Stir in the garlic and shallot, and cook until the shallot has softened and turned translucent, about 3 minutes. Add the remaining 3 tablespoons of butter, then stir in the mushrooms once the butter has melted. Cook and stir the mushrooms until they begin to soften, about 5 minutes.

Step 2

Pour in the beef broth, wine, and Worcestershire sauce; season with the bay leaf and thyme, and bring to a simmer over medium-high heat. Once simmering, season to taste with salt and pepper, reduce the heat to medium-low, and continue to cook, uncovered until the sauce reduces slightly, about 30 minutes. Dissolve the cornstarch in the cold water, and stir into the simmering sauce until thickened. Remove the bay leaf before serving.