Want a party trick that will really knock your friends’ socks off? All you’ve got to do is (1) pretend you’re in college again and buy some black lights, and (2) learn how to make glow-in-the-dark buttercream. Your cake decorating may never be the same.
This is a method originally dreamed up by blogger Recipe Snobs, and it’s fantastic for causing a stir. The icing looks like it has a candy coating or glaze — interesting, but an otherwise unremarkable buttercream technique. But then, when you turn out the regular lights and cue the black light, the buttercream will take on a ghostly glow. Amazing!
So what’s the magic trick?
Alas, no magic, but certainly science. The trick lies in tonic water. Turns out, the bitter quinine in the brew glows blue-white under a black light. So when the quinine-containing tonic water is used as an ingredient in buttercream, and then on a glaze to coat it, your confection will glow.
Tip: A few other substances will glow under a black light, too, including, but not limited to, vitamins A and B, chlorophyll, and oddly enough, brown spots on bananas.
How does this science experiment translate to buttercream?
This buttercream gets its glow in two ways, because the tonic water is used both in the buttercream itself and a viscous Jell-O and tonic water glaze to brush on top. For best results, use both the buttercream and the glaze.
Is it dangerous?
Not at all. Everything in this recipe is a food-safe item, so unless you have an allergy or aversion to tonic water or Jell-O, it’s 100 percent safe. And though tonic water is frequently used in cocktails, it doesn’t actually contain alcohol itself, so the buttercream is safe for kids, too.
Can I use diet tonic water?
Yes, as long as it contains quinine, diet tonic water will work in this recipe, too.
Can I tint it any color?
We tried this experiment in green and white; the white definitely glowed brighter. Comments on the aforementioned Recipe Snobs post revealed that for most bakers, next to white, the color green was the most successful.
How can I use this glow in the dark buttercream?
Any way you wish. You can use it to top cupcakes or a layer cake, either simply spread or prettily piped. You can top a cookie with it and then coat it with chocolate, so it’s a hi-hat confection with a glow-in-the-dark secret. Basically, any method that will allow you to brush the liquid on top without ruining your confection will work.
How to make glow-in-the-dark buttercream
Makes enough to ice 24 cupcakes, one 2-layer 8″ or 9″ cake, or 24 cookies
- 1 cup butter, softened (or 1 cup shortening)
- 1 teaspoon clear vanilla extract
- 5 tablespoons tonic water
- 6 to 8 cups confectioners’ sugar
- Food coloring, if desired
- 3 ounce package Jell-O (in the color and flavor desired)
- 1 cup boiling water
- 1 cup chilled tonic water
Start by preparing the buttercream. In the bowl of a stand mixer fitted with the paddle attachment, cream the butter on medium speed until light and very fluffy, 3 to 5 minutes.
Stir in the vanilla extract, 5 tablespoons of tonic water, and 4 cups of the confectioners’ sugar. Mix on low speed until combined, scraping down the sides of the bowl if necessary with a rubber spatula.
Add the remaining confectioners’ sugar, one cup at a time, until a spreading or piping consistency has been reached. Stir in the food coloring until combined, if using. Cover with plastic wrap and set aside for the moment.
Ice whatever you’d like to ice with the buttercream, and set it in the freezer for at least an hour, or even overnight, so the buttercream can get quite firm, even a bit hard. For this project, we tried both cupcakes with white buttercream and a cake with green buttercream.
Once the buttercream is very firm to the touch, prepare the glaze. Place the Jell-O powder in a bowl that will allow you enough room to dip your cupcakes or cookies; otherwise, you can use a pastry brush to apply the glaze.
Boil one cup of water, and then add it to the Jell-O mix. Whisk for about 1 minute, or until thoroughly combined. Add the chilled tonic water and continue whisking.
Basically, you’ll be preparing the Jell-O per the package instructions, but instead of one cup of boiling water and one cup of chilled water, you’re using boiling water and chilled tonic water.
To help the Jell-O mixture cool, you can place it in an ice bath to hasten the process. Or, simply wait until it is cool to the touch but still liquid. You just don’t want the Jell-O to start setting.
It’s time to brush or dip your buttercream-topped treats. Take several of the treats out at a time from the freezer. Either dip in the Jell-O mixture, so that only the buttercream gets dipped, or brush it on top of the buttercream.
Try to avoid the cake or pastry as much as possible, focusing on the icing. Let excess Jell-O drip off, and transfer back to a plate. Put each treat back in the freezer between dippings. For thorough coverage and the best results, you will want to dip each treat six times.
Once they’ve all been dipped six times, place them in the refrigerator for about 15 minutes so that the Jell-O glaze can set.
For best results, serve under a couple of black lights, and be sure to have the cake or cupcakes quite close to the light. Watch your friends’ faces light up as they see your treats glow.