Cleanup is easy with this one pan dinner (you'll make the sauce in the same pan you used to cook the cutlets). Serve the dish over mashed potatoes or with a loaf of crusty bread to sop up the earthy sauce. To cut costs, purchase fresh herbs labeled "poultry blend." You'll get an assortment of herbs for the price of one package.
Halve each chicken breast lengthwise to form 4 cutlets. Place each cutlet between 2 sheets of heavy-duty plastic wrap, and flatten to 1/4-inch thickness, using a rolling pin or flat side of a meat mallet. Discard plastic. Sprinkle salt and pepper over both sides of chicken. Place flour in a shallow dish, and stir in chopped thyme and rosemary. Dredge chicken in flour mixture; shake off excess. Cook 2 cutlets in 4 1/2 tsp. hot oil in a large skillet over medium-high heat 2 to 3 minutes on each side or until done. Remove cutlets from pan, and repeat procedure with 4 1/2 tsp. oil and remaining 2 dredged cutlets. Add remaining 1 Tbsp. oil to drippings in skillet; add mushrooms, and sauté over medium-high heat 4 to 6 minutes or until browned and all moisture evaporates. Stir in vinegar, and cook, stirring occasionally, 1 to 3 minutes or until liquid evaporates. Stir in broth and sage; bring to a boil. Boil until liquid is reduced to about 1/4 cup. Remove from heat; stir in mustard. Whisk in butter, 1 Tbsp. at a time. Spoon sauce over cutlets.