Preheat oven to 350 degrees. Spray a 9x13 cake pan with nonstick cooking spray.
In a large mixing bowl, add in the chocolate cake mix, water, vegetable oil, and eggs. Beat with a hand mixer on medium until incorporated.
Pour into the prepared pan and set aside.
Peanut Butter Cheesecake
In a medium mixing bowl, add in the butter, cream cheese, and peanut butter. Beat on medium with a hand mixer until creamed.
Add in the brown sugar, powdered sugar and vanilla extract. Beat on medium until combined.
Scoop spoonfuls of peanut butter cheesecake filling all over the top of the cake batter. Make sure to distribute the filling pretty evenly.
Sprinkle the chocolate chips and peanut butter cups all over the top of the cake and peanut butter cheesecake filling.
Place into the oven and bake for 45 minutes or until done. Insert a toothpick and if it comes out clean or with moist crumbs, the cake is done. There may be some chocolate from the chocolate chips but it will look like melted chocolate rather than cake batter.
Let the cake cool completely.
Cut and serve! Store in the fridge.
Double the peanut butter cheesecake for a gooier cake!