Speedy Little Devils

1 (18.25 ounce) box devil's food cake mix
1/2 cup (1 stick) margarine, melted
1/2 cup peanut butter, smooth or crunchy
1 (7 ounce) jar Marshmallow Cr�me

Heat oven to 350 degrees F. Grease a 13 x 9-inch baking pan.

Combine cake mix and margarine in a bowl and blend until crumbly. Reserve 1 cup for topping. Press remaining cake mix mixture into prepared baking pan. Spread peanut butter over cake mixture; spread Marshmallow Cr�me over peanut butter. Bake for 20 minutes. Cool and cut into bars.