Slice defrosted chicken breasts on a diagonal, then place one at a time inside a quart-sized ziplock bag. Pound with the flat side of a mallet until evenly thinned (approximately ¼ inch thick). Repeat with the remaining chicken. Season both sides with ¼ teaspoon salt and pepper.
Mix flour with ½ teaspoon salt, and ¼ of pepper, crushed red pepper, and cayenne. Dredge each piece of chicken in the flour to coat on both sides, then shake off excess flour.
Heat olive oil in a large skillet over medium-high heat until shimmering. Add coated chicken pieces and cook for about 1½—2 minutes per side, just until lightly golden but not cooked through. Remove from pan and set aside.
Add butter to pan; sauté shallots, mushrooms, and garlic for a few minutes over medium heat. Add wine and broth to deglaze the pan, then add ¼ teaspoon crushed red pepper. Place chicken in the pan and cook, uncovered, over low to medium heat for 3 minutes per side. Taste the sauce and adjust seasoning, if needed. Top with chopped Italian parsley.
Serving Instructions
Serve chicken scallopini smothered in the sauce over pasta or white rice. Or serve with some crusty bread to soak up the delicious sauce, and a broccoli crunch salad.
Notes
Partially frozen chicken breasts are much easier to slice thinly and evenly.
Pound the chicken just until evenly thin, not paper-thin.
Use just enough flour to coat.
Taste the sauce and adjust the seasoning if necessary before serving.
Finish with fresh parsley, basil, oregano, or thyme. Dried herbs are fine to simmer in the sauce, but fresh herbs at the end take it to the next level.
Store leftovers in an airtight container in the fridge for up to 4 days.