Place chicken between sheets of waxed paper and flatten with a mallet.
In a shallow dish, combine flour, salt and pepper. Dredge chicken pieces until well-coated, shaking off excess flour.
In a saute pan over medium-high heat, melt butter and olive oil. Add chicken and brown well, turning often to prevent sticking, for approximately 2 to 3 minutes.
Add Marsala wine and chicken broth. Cover, reduce heat to low and simmer for 3 minutes. Sprinkle with Parmesan cheese and cover until cheese has melted.
Remove chicken and place on warmed plate. Pour lemon juice into pan and whisk pan juices and browned bits together. Pour sauce over chicken. Serve immediately.