Start by cutting your pork loin filet into about 1-inch cubes. In a medium-size skillet over medium-high heat, add the olive oil and pork cubes. Cook 3 to 4 minutes on each side, until pork is brown and cooked throughout. Remove and set aside on a plate.
Add the minced garlic and mushrooms to the skillet and cook for 2 to 3 minutes or until tender. Set aside on the plate with the pork.
Add the chicken broth and Marsala wine, bring to a boil, and allow it to deglaze for about 1 to 2 minutes. Add in the heavy cream, ground mustard, and garlic powder. Add in a cornstarch slurry (mix the cornstarch with 2 tablespoons water in a small bowl) by pouring into the sauce. Let simmer until thick for about 5 to 7 minutes.
Put the pork and mushrooms back into the sauce and heat through. Serve over rice, noodles, or mashed potatoes.