Even though this may not be the Peanut Butter Cake you are looking for.....at least it is a Peanut Butter Cake!

Peanutbutter Cake with Chocolate Peanut Butter Frosting
1/3 cup butter, softened
2¼ cups cake flour, sifted before measuring
1½ cups granulated sugar
1 tablespoon baking powder
1 teaspoon salt
1/3 cup creamy peanut butter
1 cup milk
2 eggs
1 teaspoon vanilla extract
Chocolate Peanutbutter Frosting, below

Cream butter until light and fluffy. Sift in flour, sugar, baking powder, and salt. Add peanut butter and 2/3 cup of the milk. Mix until flour is well moistened. Beat for 2 minutes on low speed of electric hand-held mixer. Beat in remaining 1/3 cup of milk, the eggs, and vanilla. Beat for 2 minutes.
Grease and flour two 9-inch layer cake pans; pour batter into the pans. Bake at 375° for about 25 minutes, or until a wooden pick or cake tester inserted in center comes out clean. Cool, carefully remove from pans, frost, and assemble layers.
Chocolate Peanut Butter Frosting: 1/2 cup peanut butter 1/3 cup unsweetened cocoa 2 3/4 cups sifted powdered sugar 1/4 teaspoon salt 1 teaspoon vanilla extract 1/2 cup half-and-half or evaporated milk
Cream together the peanut butter and cocoa. Add the sifted powdered sugar, salt, and vanilla, and about 1/2 cup of cream. Beat until smooth, adding a little more cream for a good spreading consistency, if necessary.

Here is a link that might be useful: A Peanut Butter Cake