Heat 2 Tbsp. of the oil in a large skillet over medium-high heat. Season the pork with salt and pepper, and then coat in flour, shaking off excess. Reserve the excess flour. Place the cutlets in the skillet and cook 3-4 minutes per side, and then transfer to a plate. Lower the heat to medium and add the remaining 1 Tbsp. of oil. Add the shallots and mushrooms to the skillet and cook, stirring, until tender, about 4-5 minutes. Stir 3 Tbsp. of the reserved flour into the pan. Slowly pour in, stirring constantly, the chicken stock. Add the sage and bring to a simmer. Stir in the whipping cream. Return the pork to the pan and heat through. Adjust seasoning and serve.