Preheat oven to 350°F. Heat oil in a medium skillet over medium-high heat. Add chicken breasts and sauté until tender. Meanwhile, prepare scalloped potatoes according to package directions, adding milk and sliced potatoes. When chicken is tender, remove from heat, let cool and shred. Add shredded chicken to potato mixture and fold all into a 9 x 13-inch baking dish. Cover and bake for 25-35 min. Add cheese and bake for another 10 min.