Peanut butter lovers unite! This cake is so moist, and the frosting so creamy. The crunch of the peanuts on top just makes it so, so good! It's a hit at pot lucks, and I never have any left overs to bring home. Okay, I swipe a couple of pieces and hide them away for myself before I leave the house. Got to make sure the cook gets some for later. :o)
CAKE: Combine flour, sugar, salt and baking soda in a large bowl; set aside. Combine butter, water, and peanut butter in a saucepan over medium heat; bring to a boil. Add to flour mixture and mix well; set aside. Combine eggs, vanilla and buttermilk; add to peanut butter mixture.
Spread batter in a greased 15"x10" jelly-roll pan. Bake at 350 degrees for 25 to 28 minutes or until cake springs back when gently touched. Spread Peanut Butter Icing over warm cake and garnish, if desired.
ICING: Combine first 3 ingredients in a saucepan over medium heat; bring to a boil. Remove from heat; stir in powdered sugar and vanilla, mixing until spreading consistency.