Preheat oven to 375°F.

Slice the mushrooms and mince the garlic.

Cut the chicken breasts in half lengthwise to make 6 thinner chicken breasts.

Season both sides of the chicken with salt and pepper, then dredge in flour. Shake off any excess.

Add olive oil and 1 tablespoon butter to a medium skillet over medium heat.

Cook 3 pieces of chicken at a time for about 3 minutes per side. Do not cook all the way through. Transfer to a casserole dish and repeat with remaining chicken.

In the same skillet, add 1 tablespoon butter. Once melted, add mushrooms and cook until slightly seared and the liquid has cooked off. Spoon mushrooms over the chicken.

Add remaining 2 tablespoons butter to the skillet. Once melted, add the extra flour and garlic. Cook for about 1 minute, stirring or whisking.

Slowly add the heavy cream and sherry or Marsala, whisking until smooth. Cook for a few minutes until slightly thickened. Season with salt and pepper to taste.

Pour the sauce over the chicken and mushrooms.

Top with Muenster cheese. Cover the casserole dish with foil and bake for about 20 minutes.

Remove foil and broil for a few minutes, until the cheese is golden and bubbly.

Let rest for a few minutes before serving.