Peanut Butter Sheet Cake

This moist cake lasts in the fridge more than a week…if there are any leftovers!


  • CAKE:
  • 1/4 c smooth peanut butter
  • 1 c water
  • 1/2 c butter
  • 1 c sugar
  • 1 c brown sugar
  • 2 c flour
  • 1 tsp salt
  • 1 tsp baking soda
  • 2 eggs
  • 1 tsp vanilla
  • 1/2 c buttermilk (milk with 1/2 tsp vinegar added)
  • 3/4 c butter
  • 6 tbsp buttermilk
  • 1/2 c smooth peanut butter
  • 3 1/2 c icing sugar
  • 1 tsp vanilla


  • Heat oven to 375F
  • Grease a large cookie sheet with sides (jelly roll pan) 12″ x 17″.
  • In a large saucepan, add peanut butter, water and butter and bring to a boil.  Remove from heat.
  • In a separate bowl, mix sugar, brown sugar, flour, baking soda and salt.  Stir well.  Add to peanut butter mixture and stir until completely combined.
  • Add the eggs, vanilla, and buttermilk.  Mix well and pour into greased pan.  Bake for 15 min until centre springs back when touched.  Remove from oven.
  • While cake is cooking, in a medium saucepan, bring butter, buttermilk and peanut butter to a boil.  Remove from heat and add icing sugar and vanilla.  Whisk until completely combined.
  • Let cake sit for 3-5 minutes after removing from oven.  Pour frosting over warm cake.
  • Enjoy

Thanks to Ashley for sharing!!

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