Scoop one tub of frosting into a bowl. Scoop another tub of icing into a second bowl.
Add a small amount of blue gel food coloring to one bowl and mix well. Add more food coloring and stir until you get the color you want.
Repeat with red food coloring in the second bowl to make the red icing.
Cut off the tip of the piping bag (if using disposable).
Insert one piece of the coupler into the tip of the piping bag. Insert the icing tip into the other piece of the coupler, then screw it in place onto the piece on the piping bag.
Fill your piping bag with the blue frosting. Squeeze out any air at the open end of the bag and tightly twist the bag closed.Repeat with the red and white frosting bags.
Step 2: Frost cupcakes
Start by piping the blue frosting around the outside edge of the cupcake. Apply pressure to the piping bag. Slowly release pressure on the piping bag while simultaneously pulling the piping bag away from the cupcake. This allows the frosting to form long strings.The longer you keep applying pressure and pulling, the longer the frosting strings will be.
Create a second ring of blue frosting inside the first using the same technique.
Remove the piping tip from the blue bag and clean it before attaching it to the bag with white frosting. Using the same technique, pipe a ring of white frosting inside the blue ring of frosting.
Remove the tip from the white icing bag, clean it, and attach it to red icing bag. Now add a small ring of red icing in the centre of the cupcake with red, using the same technique once again.
Your firework cupcake is complete!
Video
Notes
The icing colors will get darker the longer they sit after the food coloring is added. Feel free to make these cupcakes the night before and you'll wake up to slightly brighter colors in the morning.