Preheat oven to 350 degrees F. Line a 9 by 13-inch baking pan with foil, extending the sides of the foil over the edges of the pan. Spray the foil liberally with cooking spray; set aside.

In a large bowl, combine the cake mix, melted butter, egg, and old-fashioned oats and stir together until combined and a thick dough has come together. Press the dough evenly into the bottom of the prepared pan. Bake for 12 minutes, then remove from the oven but keep the oven on.

Sprinkle the top of the crust evenly with the chopped oatmeal creme pies and both butterscotch and white chocolate chips. Pour the condensed milk evenly over the top. Return to the oven and bake for an additional 18-20 minutes or until the top is set and bubbly.

Cool the bars in the pan completely to room temperature before cutting and serving.