In a microwave, melt shortening and chocolate; stir until smooth. Set aside. In a large bowl, beat eggs, sugar and 1 teaspoon vanilla. Gradually add the flour, nuts, salt, baking powder and chocolate mixture.
Pour into a greased 8-in. square baking pan. Bake at 350° for 20-25 minutes or until a toothpick inserted near the center comes out clean. Cool on a wire rack. Cut into 2-in. x 1-in. rectangles; remove from pan.
In a large bowl, beat the confectioners' sugar, cream and remaining vanilla until smooth; set half aside. Spread remaining frosting over top of brownies. Tint half of the reserved frosting red and half green.
Cut a small hole in the corner of two plastic or pastry bags; fill one bag with red frosting and one with green. Insert pastry tip if desired. To decorate, pipe ribbon and bows on brownies or create designs of your choice. Yield: 2-1/2 dozen.