Roll out fondant 1/18 in. thick. Cut out 13 stars using second smallest star from cutter set. Lay on waxed paper and let dry overnight.
Brush piping gel on front of stars and sprinkle with white sparkling sugar. Let dry. Attach lollipop sticks with fondant adhesive. Let dry.
Preheat oven to 350°F.
Prepare each package white cake mix following package instructions using water, oil and egg whites. Keep batters separate!
Gently stir Red-Red and Christmas Red Icing Color to desired shade into 1 bowl of batter (use clean toothpicks to transfer color from jar to batter); repeat with Royal Blue Icing Color and 1 bowl of batter. Reserve 1 bowl of batter white.
Place batter dividing ring into first pan; spray pan and ring with vegetable pan spray.
Fill each section two-thirds full as follows: red-tinted batter in center, white batter in middle section, blue-tinted batter in outside section. Gently tap pan on counter; remove ring and wash well.
Repeat in second pan, filling center with white, middle section with blue and outside section with red batter. Gently tap pan on counter; remove ring and wash well.
Repeat in third pan, filling center with blue, middle section with red and outside section with white batters. Gently tap pan on counter; remove ring and wash well.
Bake 30-35 minutes or until toothpick inserted in center comes out clean. Cool in pan 10 minutes. Remove from pan and cool completely.
Make buttercream icing. Tint a portion blue and a portion red; reserve some white.
Stack cake layers on a foil-wrapped cake board with thin layer of white buttercream icing between layers. Ice sides with thin layer of white buttercream icing. Ice top of cake smooth with blue buttercream icing.
Prepare two decorating bags with tip 21. Fill one bag with red buttercream icing and the other with white buttercream icing. Starting from the bottom, pipe red stars in a single row.
Then, pipe stars with white buttercream icing in a single row. Repeat until you reach top of cake, ending with a red row.
Insert stars into cake top.
*Combine Red-Red with Christmas Red for red icing used.
The star tip creates the most celebrated, easily accomplished decorations! The serrated edges of the star tip make ridges in the icing as you squeeze it out. Because fill in requires so much piping from the same bag, keep replenishing icing in bag.