Salt and flour chicken breast, pat off excess flour.
When oil is hot, sauté chicken breast until browned on both sides, remove breast.
Leaving oil in pan, add mushrooms and onions, and a pinch of salt and pepper. sauté.
When mushrooms and onions are sauteed add marsala, demi glace, and cream, and another pinch of salt.
Reduce until bubbles start to slow and sauce thickens, add chicken breast for one minute and turn off heat, flip the chicken breast in the sauce and serve when ready, pour sauce over chicken breast.