Prep the chicken: If using large breasts, slice them in half horizontally to create thinner cutlets. Pat dry. Season both sides with salt, pepper, and a light dusting of garlic powder and onion powder.

Dredge lightly: Place flour in a shallow dish. Dredge each piece of chicken, shaking off excess. You want a thin, even coating that helps with browning and thickens the sauce later.

Sear the chicken: Heat 1–2 tablespoons oil and 1 tablespoon butter in a large skillet over medium-high heat. Sear chicken in batches for 2–3 minutes per side, until lightly golden. Do not cook through. Transfer to a 9x13-inch baking dish in a single layer.

Sauté the mushrooms: In the same pan, add another tablespoon of butter if needed. Add sliced mushrooms with a pinch of salt. Cook over medium heat for 5–6 minutes, stirring occasionally, until they release moisture and begin to brown. Add minced garlic and cook 30 seconds more.

Deglaze: Pour in the sherry or white wine. Scrape up browned bits and let it simmer for about 1 minute to reduce slightly. If skipping wine, add a splash of broth instead.

Build the sauce: Stir in chicken broth and the cream of mushroom soup. Bring to a gentle simmer. Turn off the heat and whisk in heavy cream or sour cream, plus the Parmesan. Taste and adjust salt and pepper. The sauce should be creamy and well-seasoned.

Assemble: Pour the mushroom sauce evenly over the chicken in the baking dish. Sprinkle shredded mozzarella or Swiss on top.

Bake: Cover loosely with foil and bake at 375°F (190°C) for 20 minutes. Remove foil and bake another 10–15 minutes, until the cheese is melted and lightly golden and the chicken reaches 165°F (74°C) in the thickest part.

Rest and garnish: Let it rest 5–10 minutes so the sauce settles. Sprinkle with chopped fresh parsley.

Serve: Spoon chicken and plenty of sauce over rice, pasta, mashed potatoes, or roasted vegetables. Add a green salad on the side for balance.