1. Mix flour, sugar, salt and baking soda. Set aside.
2. Bring peanut butter, water, and butter to a rapid boil.
3. Pour over flour mixture and stir well.
4. Add eggs and buttermilk.
5. Mix well.
6. Pour batter into greased 1- X 15 sheet pan.
7. Bake at 350 for 20-25 minutes.
8. For Frosting; Mix melted butter and peanut butter together.