Preheat the oven to 375 F.
Season the chicken with salt and pepper.
Dip each piece of chicken into the flour, shaking off any excess.
Heat 2 tablespoons of olive oil in a large skillet over medium-high heat.
Brown the chicken on both sides, then transfer to a baking dish.
In the same skillet, add 2 tablespoons of olive oil and saute the mushrooms, onion, and garlic until soft.
Transfer the sauteed vegetables to the baking dish over the chicken.
Melt the butter in the skillet, add flour, sherry, and heavy cream to make the sauce.
Season the sauce with salt and pepper, then pour it over the chicken and vegetables.
Top with Swiss cheese slices.
Cover the baking dish with foil and bake for 20-25 minutes.
Remove the foil and broil for a few seconds to melt and brown the cheese.
Garnish with fresh thyme before serving.
