CAKE: Heat oven to 350 degrees. Line 30 cm pizza pan with aluminum foil. In medium bowl, stir together margarine, sugar and vanilla. Add eggs. Beat well with spoon.
Combine flour, cocoa, baking powder, and salt. Gradually add to egg mixture, stirring until well blended. Spread batter in prepared pan. Bake 20 to 22 minutes or until top springs back when touched lightly in center. Cool in pan on wire rack.
Trim off any edges that may have gone over the side of the pan.
If desired, remove brownie from pan. Peel off foil , or serve in pan. Spread frosting over top. Draw holly leaves on frosted brownie and place red candies in proper place to look like holly berries.
FROSTING: In a small bowl, beat margarine. Gradually add powdered sugar, milk, and vanilla, beating until desired consistency.