In a large bowl or plate add flour, salt, and pepper. Coat the chicken in the mixture.
In a large skillet over medium-high heat, warm the olive oil. Add the chicken and cook until golden, flipping midway.
Transfer the chicken from the skillet and set aside.
Melt the butter in the skillet. Add onions and mushrooms. Cook until the mushroom liquid evaporates and the onions soften.
Toss in the garlic and cook, stirring, for about 1 minute until fragrant.
Pour the marsala into the mushroom mixture and simmer until reduced by half.
For the creamy sauce, add the cream and chicken stock, bringing it to a simmer.
Place the chicken back in the pan along with any resting juices.
Simmer for 5 minutes, turning once, until the chicken is fully cooked and the sauce slightly thickens.
Optionally, garnish the chicken with fresh parsley before serving. Enjoy!