Peanut Butter Sheet Cake

So, it turns out I really like these sheet cakes. I’ve done chocolate, vanilla, and caramel sheet cakes, and today I decided to try a peanut butter version. I’m not sure what it is that helps these particular gluten free cakes to be so soft and light (I suspect the boiling water), but they’ve just been delicious. This peanut butter cake was no exception. Everyone liked it, even my daughter’s college roommate who, as a general rule, doesn’t like peanut butter things. Give it a try and tell me what you think!

Peanut Butter Texas Sheet Cake

2 c. EGF all-purpose flour
2 c. sugar
1 tsp. xanthan gum
1 tsp. baking soda
1/2 tsp. salt
1/2 c. butter (1 stick)
1/2 c. creamy peanut butter
1 Tbs oil
1 c. water
1/2 c. buttermilk (I use 1/2 c. whole milk plus about 1.5 tsp. lemon juice)
3 eggs
1 tsp. vanilla

In a large bowl, combine flour mix, sugar, xanthan gum, baking soda, and salt. In a medium pan, combine butter, peanut butter, oil, and water. Bring to a boil over medium high heat, stirring regularly. (Don’t worry if the peanut butter mixture starts to look separated - it will all mix in well in the end). Pour peanut butter mixture into flour mixture and mix well until smooth. Add buttermilk, eggs, and vanilla and mix thoroughly. The batter will be thin.

Pour batter into a greased (or well-sprayed-with-Pam or parchment-paper-lined) 13x18 sheet cake pan. Bake at 400 degrees for 20-25 minutes. (The edges of the cake will start to pull away from the pan when the cake is done, and the center of the cake will bounce back if gently touched (don’t burn yourself!).) Remove from the oven and, while hot, top with the following frosting:

Peanut Butter Frosting

1/2 c. butter (1 stick)
1/2 c. peanut butter (creamy or crunchy)
3 1/3 c. powdered sugar (just under 1 lb.)
6-7 Tbs. milk
1 tsp. vanilla

Place powdered sugar in the bow of a stand mixer. Combine butter, peanut butter, and milk in a medium saucepan over medium-high heat, stirring continually, until mixture starts boiling.  (Again, don’t worry if the mixture separates some.) Turn the mixer on low and slowly pour the hot peanut butter mixture into the powdered sugar while the mixer is running.  Mix on medium speed until the powdered sugar is well-incorporated and the icing is smooth, then add the vanilla.

Pour immediately over warm cake and gently spread. (Frosting will firm up quickly and spreads best while still hot.)