Chicken Marsala - Once Upon a Chef

Ingredients

• 1½ pounds boneless skinless chicken breasts, (pounded ¼-in (6-mm) thick (see note), or chicken tenderloins)
• 3 tablespoons all-purpose flour
• Salt
• Freshly ground black pepper
• 1 tablespoon olive oil
• 3 tablespoons unsalted butter, (divided)
• 1 (8-oz) package pre-sliced bella or button mushrooms
• 3 tablespoons finely chopped shallots, (from 1 medium shallot)
• 2 cloves garlic, (minced)
• ⅔ cup chicken broth
• ⅔ cup dry Marsala wine
• ⅔ cup heavy cream
• 2 teaspoons chopped fresh thyme
• 2 tablespoons chopped fresh Italian parsley, (for serving (optional))