Make chocolate cake recipe according to directions and cool completely.
Make chocolate frosting recipe according to directions and fill and frost cakes together.
In a small bowl, stir peanut butter together with powdered sugar, vanilla and milk. Stir until smooth and then continue adding more milk, little by little, until desired consistency is reached.
Using a teaspoon, drip the peanut butter glaze down the sides of the cake and then spoon over the top and spread gently to cover completely.