Pat chicken breasts dry with paper towels. If breasts are thick, butterfly and then gently pound to an even thickness of about 1/2 inch between sheets of plastic wrap or in a resealable bag using a meat mallet or rolling pin.

Season both sides of each chicken breast with 1/4 tsp kosher salt and a pinch of black pepper (reserve remaining salt and pepper for later).

Place the flour on a shallow plate and dredge each seasoned breast lightly, shaking off excess flour so there is a thin coating.

Heat a large skillet (preferably stainless steel or cast iron) over medium-high heat. Add 2 tbsp olive oil and 1 tbsp butter. When butter foams and oil shimmers, add the chicken breasts (work in two batches if necessary to avoid crowding).

Pan-sear chicken until golden brown, about 3-4 minutes per side depending on thickness. Internal temperature should reach 160°F (71°C) as it will finish cooking in the sauce. Transfer cooked chicken to a warm plate and tent loosely with foil.

Mushrooms & Aromatics

In the same skillet with the fond (browned bits), reduce heat to medium. If the pan is dry, add 1 tsp olive oil. Add the sliced mushrooms in a single layer and let them sear without moving for 2 minutes to develop color, then stir and cook another 2-3 minutes until browned and any released liquid has mostly evaporated.

Add the finely diced shallots and cook 1-2 minutes until softened and translucent. Add minced garlic and thyme and cook 30-45 seconds until fragrant, taking care not to burn the garlic.

Sauce & Deglaze

Raise heat to medium-high. Pour in 3 tbsp Marsala wine to deglaze the pan, scraping up browned bits from the bottom with a wooden spoon. Let Marsala reduce by about half, roughly 1-2 minutes.

Add 3 tbsp low-sodium chicken stock and bring to a gentle simmer. Allow the liquid to reduce slightly, about 1-2 minutes, concentrating flavor.

Reduce heat to low and stir in 1/4 cup heavy cream. Simmer gently 1-2 minutes until sauce is slightly thickened and glossy. Taste and adjust seasoning with remaining 3/4 tsp kosher salt and remaining black pepper as needed.

Whisk in 1 tbsp unsalted butter (for finishing) off the heat to enrich and slightly thicken the sauce.

Return the seared chicken breasts and any accumulated juices to the skillet, spooning sauce and mushrooms over the chicken. Simmer on low for 2-3 minutes to warm through and complete cooking to 165°F (74°C) if needed.

Finish & Serve

Transfer chicken to plates, spoon mushrooms and Marsala sauce over each breast. Sprinkle chopped parsley on top and serve with lemon wedges on the side. Recommend serving with mashed potatoes, buttered pasta, or roasted vegetables to catch extra sauce.