On a plate, stir the flour, salt, pepper, garlic powder, and onion powder.
Dredge the chicken breasts in the flour mixture.
Heat several teaspoons of oil on medium heat. Add two chicken pieces of chicken at time. You don't want to crowd the pan. Cook each piece of chicken for about 2 minutes per side. Repeat with all the chicken pieces. You want the chicken to get a little color. Remove the chicken and set aside.
Lower the heat to low-medium. Add several more teaspoons of oil to the pan, along with a tablespoon of butter. Add the mushrooms. Cook until the mushrooms begin to soften. Add the garlic. Cook until the garlic begins to soften.
Add the Marsala wines. Then, add the chicken stock. Raise the heat back up to medium. Cook until the liquid reduced by about half.
At this point, add 2 more tablespoons of butter. Allow it to melt into the sauce.
Stir in the heavy cream.
Return the chicken back to the pan. Cook until the chicken has warmed through.