1. Heat oven to 350 degrees.
2. Mix cake mix, peanut butter, oil, and egg.
3. Press cake mix into the bottom of a 9x13 greased pan.
4. Top crust with peanut butter chips, chocolate chips, and mini peanut butter cups.
5. Pour sweetened condensed milk over everything.
6. Bake for 25-30 minutes.
7. Allow to cool completely before cutting into bars.