- 1
Spread 1/4 cup flour in shallow dish. Pat chicken dry with paper towels and season with salt and pepper. Working with 1 breast at a time, dredge breasts in flour.
- 2
Heat oil in 10-inch skillet over medium-high heat until just smoking. Lay chicken in skillet and cook until well browned on first side, 6 to 8 minutes. Flip chicken, reduce heat to medium, and continue to cook until chicken registers 160 degrees, 6 to 8 minutes; transfer to plate and tent loosely with aluminum foil.
Timer: 8m - 3
Melt 1 tablespoon butter in now-empty skillet over medium heat. Add mushrooms and onion and cook until mushrooms have released their liquid and vegetables are softened and lightly browned, 5 to 7 minutes. Stir in garlic and cook until fragrant, about 30 seconds; transfer mixture to bowl.
Timer: 7m - 4
Add remaining 1/2 teaspoon flour to again-empty skillet and cook over medium heat for 1 minute. Whisk in Marsala and broth, scraping up any browned bits. Bring to simmer and cook until sauce is slightly thickened, about 5 minutes. Return chicken and any accumulated juices to skillet and simmer.
Timer: 1m - 5
Off heat, whisk in remaining 2 tablespoons butter and parsley into sauce and season with salt and pepper to taste. Pour sauce over chicken and serve.