1. Bake according to package directions in a 13x9x2-inch pan. Cool 10 minutes on wire rack; remove from pan. Cool completely. Prepare Creamy White Frosting.
Remove 3/4 cup frosting and set aside. Remove 3/4 cup frosting; add enough blue food coloring to make desired color. Remove 1/2 cup frosting; add enough yellow food coloring to make desired color. Set colored frostings aside.
2. Cut the cake as shown in the Cake Cutting Diagram (see next page). Assemble cake pieces on a large serving tray, using white frosting to attach pieces.
3. Frost the top and sides of cake with white frosting.
4. Fill a pastry bag fitted with a star tip (#28 or #35) with reserved 3/4 cup white frosting. Decorate cake as desired. Before piping the lettering, use a toothpick to outline a guide on the white frosting. Using a pastry bag fitted with a writing tip (#2, #3, or #4) and some of the blue frosting, draw the outline of a Hebrew letter on top of cake. With a pastry bag fitted with the star tip and remaining blue frosting, fill center of the letter. Using a pastry bag fitted with the writing, star, or rose tip (#104) and reserved yellow frosting or any remaining blue frosting, add additional decorations to cake. Makes 12 to 16 servings.
Use a large knife and a metal spatula to cut and maneuver the two triangles. Hint: Turn the entire cake out onto the serving tray, positioning it off-center so the cake is closest to one end. Then you'll only have to move the two triangles.