Season chicken with salt and pepper. Dredge in flour and shake off excess.

Heat 2 tablespoon olive oil in large skillet over medium-high heat. Sear chicken 5–6 minutes per side until golden and cooked through. You'll know it's ready to flip once it releases from the pan. It sticks because the crust is still forming, so don't nudge it around if it's not releasing. The protein will almost always tell you when it's ready. Remove and set aside.

Lower heat to medium, add remaining 2 tablespoon olive oil, and sauté mushrooms until golden brown, about 4–5 minutes.

Deglaze with Marsala wine, scraping up browned bits. Simmer until reduced by half. Taste it as you go. If you feel astringency at the back of your throat, the alcohol hasn't cooked off yet. Keep going until it turns round and caramel.

Add chicken broth and simmer again until reduced by half.

Lower heat to low. Stir in 2 tablespoon butter until emulsified.

Return chicken to the skillet and simmer for 5 more minutes to absorb flavor.

Season with salt and pepper to taste, garnish with chopped parsley, and serve.