Sprinkle the chicken with salt and pepper. Dip the chicken into the flour; shake off the excess.
In a large skillet, melt 3 tablespoons of butter in a large skillet over medium-high heat. Add the chopped sage; sauté 1 minute. Add half of the chicken. Sauté until brown and cooked through, about 3 minutes per side.
Transfer the chicken to a platter. Repeat with the remaining butter and chicken. Tent the platter with foil to keep the chicken warm.
Add the marsala and broth to the skillet; bring to a boil, scraping up any browned bits. Add the mushrooms. Boil until the sauce is reduced to ½ cup, about 10 minutes. Season with salt and pepper; spoon over the chicken. Garnish with fresh sage leaves; serve.
Notes
*If you are preparing this recipe as GLUTEN FREE, just be sure to use a brand of chicken broth that is designated as gluten free. And use GF flour in place of all-purpose.