Heat oven to 350°F. Lightly grease 9-inch round cake pan.
Cut pouch open at top corner.
Squeeze entire pouch of batter into prepared pan and spread evenly.
Dollop peanut butter over top of batter and use a knife or spatula to make swirl designs.
Bake for 28-32 minutes or until a toothpick inserted into the center comes out clean.
Allow cake to cool completely before cutting or removing from pan.