Melt butter in a saute pan over Medium Heat.
Add in the Shallot and season with a pinch of Salt and Pepper. Sauté 1-2 minutes, or until softened.
Add the Mushrooms to pan. Sauté until liquid is evaporated and mushrooms are barely cooked through, about 3 minutes.
Add in the Garlic and a scant ¼ tsp Salt. Sauté until fragrant, about 30 seconds.
Sprinkle the Flour over mushrooms and stir to incorporate.
Reduce heat to Medium/Medium-Low and add in the Marsala Wine. Cook until slightly reduced, about 4 - 6 minutes, scraping up browned bits off bottom of the pan.
Add in the Beef Stock and continue to coo until slightly reduced again, about 4-5 minutes.
Stir in the Heavy Cream and Thyme. Reduce heat to maintain a gentle simmer. Simmer for 3-4 minutes, stirring occasionally.
Add in the Parsley. Taste and adjust for seasoning with salt and pepper.
Serve over steak, chicken, pork or pasta. Enjoy!
Yield: 1 1/2 cup sauce