01 -
Preheat the oven to 350°F (175°C) and grease a sheet cake pan.
02 -
In a large mixing bowl, combine the yellow cake mix, eggs, softened butter, creamy peanut butter, and water. Beat the mixture until smooth and well blended.
03 -
Pour the batter evenly into the prepared sheet cake pan and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
04 -
While the cake is baking, beat together the creamy peanut butter and softened butter in a separate bowl until creamy.
05 -
Gradually add the powdered sugar, milk, and vanilla extract to the peanut butter mixture, beating until smooth and spreadable.
06 -
Once the cake is done baking, allow it to cool completely in the pan. Spread the peanut butter frosting generously over the cooled cake.
07 -
Cut the cake into squares and serve.