Note For chocolate peanut butter bars, you can substitute chocolate cake mix for the yellow, or chocolate chips for the peanut butter chips.

1 (18.25-ounce) package yellow cake mix 2 large eggs, lightly beaten 1 cup chunky peanut butter 1/2 cup (1 stick) butter, melted 1 (10-ounce) package peanut butter chips 1 (14-ounce) can sweetened condensed milk

Preheat oven to 350 degree F. In a large bowl, combine cake mix, eggs, peanut butter, and butter; mix well. Press half the mixture onto bottom of an ungreased 9- x 13-inch baking dish. Bake 10 minutes. Remove peanut butter base from oven, top with peanut butter chips, and drizzle with sweetened condensed milk. Crumble remaining peanut butter mixture then sprinkle over top. Bake 25 to 30 minutes, or until golden. Allow to cool completely then cut into bars.