Peanut Butter Sheet Cake

{recipe & pic from} The Girl Who Ate Everything 

Peanut Butter Sheet Cake

recipe by Nina Jones

Mix in pan and bring to a boil:
1/4 cup creamy peanut butter
1 cup water
1/2 cup butter

Sift the following and add to the above mixture:
1 cup sugar
1 cup brown sugar
2 cups flour
1 tsp salt
1 tsp soda

Mix and add to the above mixture:
2 eggs
1/2 cup buttermilk
1 tsp vanilla

Stir well and pour into greased or parchment lined cookie sheet pan (jellyroll pan). Bake for 15 minutes at 375 degrees.

Frosting
Mix in pan and bring to a boil:
3/4 cup butter
6 Tbsp buttermilk
1/2 cup peanut butter
Take off stove and add:
3 1/2 cups powdered sugar and 1 Tbsp vanilla. Pour over warm cake.