Peanut Butter and Chocolate Cake II

Step 1
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9×13 inch pan.

Step 2
In a saucepan, combine 1 cup margarine, 1/4 cup cocoa, water, eggs, and 1/2 cup buttermilk in a saucepan. Cook, stirring occasionally, until it bubbles. Remove from heat and set aside.

Step 3
In a large bowl, mix flour, 2 cups sugar and baking soda. Make a well in the center and pour in chocolate mixture. Add vanilla and beat until smooth. Spread batter into prepared pan.

Step 4
Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool.

Step 5
In a small bowl, mix peanut butter and oil. Spread over top of cake. In a saucepan, combine 1/4 cup cocoa, 1/2 cup margarine, and 6 tablespoons buttermilk. Heat until boiling. Remove from heat and stir in vanilla. Place confectioners' sugar in a large bowl. Beat in chocolate mixture and continue mixing until smooth. Spread over cake.