Prep the chicken: Pat the chicken dry.
If using large breasts, slice them horizontally into cutlets. Season both sides with salt and pepper. If you want a light crust, dust with almond flour and shake off the excess.
Heat the pan: Place a large skillet over medium-high heat.
Add 1 tablespoon olive oil and 1 tablespoon butter (or ghee). When hot and shimmering, add the chicken in a single layer.
Sear the chicken: Cook 3–4 minutes per side until golden and just cooked through. Transfer to a plate and tent with foil to keep warm.
Don’t overcook—carryover heat will finish them.
Sauté the mushrooms: Add the remaining oil and butter to the skillet. Toss in the sliced mushrooms with a pinch of salt. Cook, undisturbed, for 2–3 minutes to brown, then stir and continue cooking until they release moisture and turn deep golden, about 6–8 minutes total.
Add aromatics: Stir in the garlic and a pinch of red pepper flakes.
Cook 30–45 seconds until fragrant, scraping up browned bits with a wooden spoon.
Deglaze with Marsala: Pour in the Marsala wine. It should bubble vigorously. Scrape the pan to loosen all the fond.
Let it reduce by about half, 3–5 minutes, to concentrate flavor.
Build the sauce: Add the chicken broth. Simmer 2–3 minutes more. Lower the heat and stir in the heavy cream until the sauce turns silky.
If you like it thicker, simmer another 1–2 minutes. Taste and adjust salt and pepper.
Return the chicken: Nestle the chicken (and any juices) back into the skillet. Spoon sauce over the top and simmer on low for 2–3 minutes to mingle flavors.
Finish with chopped thyme or parsley and a tiny squeeze of lemon, if desired.
Serve: Spoon generous sauce over each piece. Pair with cauliflower mash, zucchini noodles, roasted asparagus, or a crisp green salad.