In a large mixing bowl, combine butter and brown sugar; beat in eggs, chocolate and vanilla.

Combine the flour, baking soda and salt; add to creamed mixture alternately with sour cream.

Gradually beat in water

Pour into two greased and floured 9-inch round baking pans

Bake at 350°F for 35-40 minutes or until toothpick comes clean from the center. Cool for 10 minutes before removing from pans to a wire rack to cool completely

For frosting: cream the butter, peanut butter, confectioners' sugar! milk and vanilla in a mixing bowl until smooth; set aside

Split each cake into two layers. Place bottom layer on a serving plate; spread with about 1/2 cup of frosting. Repeat layers twice. Top the cake with the remaining frosting.

Gently press peanuts into sides of cake