Start Pasta water.

Wash and clean Chicken Breasts. Cut in half, lengthwise. Pound chicken between waxed paper with flat meat mallet to about 1/4 inch thick.

Season both sides with salt and pepper. Dredge in flour. Shake off excess flour.

Add 1 Tbsp. Olive oil to heavy bottom fry pan over medium high heat. Brown both sides of chicken, in batches. Remove to plate when browned.

While Chicken is browning, chop Onions and Garlic and slice mushrooms.

After chicken is finished, reduce heat to medium low. In the same pan saute' onions for a few minutes, until soft. Add garlic and saute' a few additional minutes.

Put pasta in boiling water and cook according to package directions.

Add Mushrooms, Sage and 1 Tbsp. Butter to Onion/ Garlic. Continue to saute' until mushrooms are slightly brown around the edges, about 5 minutes.

Pour in Marsala and scrape the browned bits off of the bottom of the pan. Cook for 2-3 minutes.

Add Chicken Stock and stir to combine. Add Chicken to warm and finish cooking. Cook an additional 5 minutes, or so.

Drain pasta, reserving about 1 cup of the pasta water.

Meanwhile, whisk together cornstarch and 1/4 cup warm water. Whisk into the Marsala sauce and cook a few more minutes.

Remove Chicken to a plate. Add pasta and some of the pasta water to the Marsala sauce and toss.

Serve immediately with Chicken.