Heat oven to 350°F. In large bowl, beat butter and sugars with electric mixer until creamy. Add egg and vanilla; beat well. Add combined flour, baking soda and salt; mix well. Stir in oats and chocolate chips; mix well. Press dough evenly into bottom of 10-inch nonstick ovenproof skillet. Bake 20 minutes or until top is lightly browned. (Do not overbake as cookie will continue to bake after it is removed from oven.) Cool about 10 minutes. Cut into 8 wedges. Serve with ice cream and, if desired, caramel topping.