• 1 cup unsalted butter, room temperature

  • ¼ cup + 1 tbsp tonic water

  • 6 cups confectioner’s sugar

  • 3 ounce packet of Jello-O (yellow or green works best)

  • 1 cup boiling water

  • 1 cup chilled tonic water

  • 24 cupcakes (make separately)



  • Place the butter in a large bowl and beat with an electric mixer until pale and fluffy. Add ¼ cup + 1 tbsp tonic water and 4 cups confectioner’s sugar and mix until combined. Add the remaining 2 cups confectioner’s sugar and beat well.
  • Place the buttercream in a piping bag fitted with a large, round tip.
  • Pipe a large swirl of buttercream onto each cupcake. Transfer the cupcakes to the fridge for at least an hour, until the buttercream is very stiff.
  • In the meantime, make the glaze. Combine the jello and boiling water and whisk until the jello has fully dissolved. Add 1 cup chilled tonic water and whisk. Allow the jello to cool to room temperature, but not so cool that it starts to set.
  • Dunk the cupcakes into the glaze so that only the buttercream is getting coated. Alternatively, you can brush the glaze onto the cupcakes with a pastry brush. Place the cupcakes in the freezer until the glaze has set, then repeat 5 more times for a total of 6 layers of glaze. 6 layers will make the cupcakes glow the brightest!
  • Serve the cupcakes under a blacklight and watch them glow!