Preheat oven to 350°. Combine cola and buttermilk in a 2-cup measuring cup.
Beat butter at low speed with an electric mixer until creamy. Gradually add sugar, beating until blended. Add eggs and vanilla; beat at low speed just until blended.
Combine flour and next 2 ingredients in a medium bowl. Add to butter mixture alternately with cola mixture, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Pour batter into a lightly greased 13- x 9-inch pan.
Bake at 350° for 30 to 35 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 10 minutes.
Meanwhile, prepare Peanut Butter Frosting. Pour over warm cake. Sprinkle with chopped peanuts.
I made this cake and followed the instructions to the letter. Even though a great photo is shown of a piece of this cake, I don't know how this recipe made it out of the test kitchen, if it was tested. The frosting is too runny. It overwhelms the cake. It's more like icing with cake rather than cake with icing. There are too many better cake recipes out there to keep this one. Out it goes.
The cake is very good, but I agree that the frosting needs to be modified. I used 2 cups of powdered sugar, and added about 1/3 cup of milk. The frosting turned out very creamy and delicious, and the cake looks much better than pictured here.
Love the cake...don't love the frosting. The cake itself is very good, It has a very tender crumb and isn't too sweet. But, on the other hand, the frosting is way too sweet, and overpowering. But that might be because the recipe makes 3 cups! Three cups? What were they thinking? That's enough for a layer cake, not a 9 x 13. If I make this again, I'll use half the frosting recipe.