1Heat oven to 350^.
Spray a 13x9-inch baking pan with Pam.
Beat cake mix, oil and egg in a large bowl on medium speed until mixture resembles coarse crumbs.
Stir in peanuts.Reserve 1 1/2 cups crumb mixture.
Press remainder on bottom of prepared pan.
Beat sweetened condensed milk and peanut butter in medium bowl until smooth.
Spread over prepared crust. Sprinkle with reserved crumb mixture.
Bake 25-30 minutes or until set. Cool. Place frosting into resealable food storage bag.
Seal bag. Microwave 5 seconds on High.
Snip small corner off bag. Squeeze bag, drizzle in a criss-cross pattern over crumb topping.
Chill to set chocolate drizzle for easy cutting into bars.