Chicken Marsala

Susan made this for Mom and Dad last night. She got this recipe from Dawn.

1 ½ pounds boneless chicken breasts
2 tbsp olive oil
5 tbsp butter
¾ cup chopped onion
1 lb cremini mushrooms
2 tbsp minced garlic
1 cup dry Marsala
1 cup mascarpone cheese
2 tbsp Dijon mustard
2 tbsp chopped flat parsley
12 oz fettuccini

 Cut chicken breasts crosswise into 3 pieces and sprinkle with salt and pepper
 Heat oil in pan and brown chicken, approximately 4 minutes per side
 Transfer chicken to a plate and cool slightly
 Add 2 tbsp butter to the same pan over medium heat
 Add onion and sauté until tender, about 2 minutes
 Add mushrooms and garlic and sauté until the mushrooms and juices evaporate, about 12 minutes
 Add wine and simmer until reduced in half, about 4 minutes
 Stir in mascarpone and mustard
 Cut chicken crosswise into 1/3 inch thick slices
 Return chicken and accumulated juices to pan
 Simmer uncovered over medium-low until chicken is cooked and sauce thickens slightly, about 2 minutes
 Stir in parsley, season to taste
 Serve with fettuccini