Heat oven to 180ºC . Grease and flour two 23 cm round cake pans. In large bowl, combine cream cheese, half cup margarine, vanilla and peppermint extract; blend until smooth. Add powdered sugar alternately with hot water, beating until smooth. Blend in chocolate. In another large bowl, combine 2 cups of the frosting mixture and quarter cup margarine; blend well. Beat in eggs 1 at a time, beating well after each addition. Add flour, baking soda, salt and milk; beat until smooth. Pour batter evenly into greased and floured pans. Bake at 180ºC for 30-40 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes; remove from pans. Cool completely. To assemble cake place 1 layer top side down on serving plate; spread with about quarter of frosting. Top with second layer top side up. Spread sides and top of cake with remaining frosting. Store in refrigerator.