This glow-in-the-dark Halloween punch is both a trick and a treat

In my never-ending quest to make your cocktails more sophisticated, I’m here to urge you to consider a neglected drink ingredient. No, I’m not talking about singani or sotol or shōchū — though yes, you should be exploring those spirits.

I’m talking about riboflavin! That’s right, riboflavin, a.k.a. vitamin B2, your ally against migraines and cataracts that comes in both liquid and powdered forms, and has a mild, grassy bitterness that pairs beautifully with ...

Oh, the hell with how it tastes. It glows, people. It glows.

Just naming a drink a “spooky spritz” or a “spooky smash” doesn’t make the drink Halloween-appropriate, or even autumnal. I want something that’s really going to fit the moment — something a little creepy or at least appropriately seasonal. And with friends who regularly use the occasion to deck their yard with enough snarling decorative gourds to keep up with the Addamses, I’m constantly in search of something that will take the night’s drink offering up a notch.

That’s why, in early October, I found myself scrubbing my T-shirt under a faucet after opening a packet of riboflavin powder a little too eagerly. Imagine the cocaine-sneeze scene in Annie Hall, only bright orange. In both liquid and powdered form, riboflavin is a glorious sunny pumpkin color, like turmeric with an afterglow. And yes, it stains. Handle with care (or wear Wednesday Addams-black when handling, so it doesn’t turn you into a pumpkin while you work). I recommend using the liquid version, which was far easier to work with.

The reason I had ordered various forms of riboflavin and thiamine (a.k.a. vitamin B1) and stocked up on tonic water was because all three ingredients glow when exposed to UV light. I was aiming to develop a drink that would look like Slimer went to sleep in a punch bowl, but could just as easily slip into a more sci-fi, Creature from the Goo Lagoon sort of vibe. I wanted the punch to be green, tasty and, most importantly, I wanted it to glow without sending anyone to the hospital. My local party supply store had multiple affordable black lights, which were the key to making this work: These lamps emit the ultraviolet light that causes specific chemicals to fluoresce.

Tonic water, of course, is easy to obtain. For those coming in too late to obtain some riboflavin or thiamine drops, you can get a decent effect with the tonic water alone, which fluoresces blue thanks to its quinine content. After a few experiments with color, taste and light, I went with the liquid riboflavin. Its flavor was mild and neutral enough to not impact the final drink’s taste, and even without the black light in play, its brilliant yellow color enhanced the other cocktail ingredients I wanted to incorporate.

Specifically, Midori, a Japanese muskmelon liqueur that disco denizens of Studio 54 no doubt remember (assuming disco denizens of Studio 54 remember much at all). Midori is very sweet and also very green, which made it perfect here. With the various ingredients all mixed together, under standard lighting you have a startlingly neon yellow, opaque drink that tastes like a melon-coconut daiquiri. But serve it under, or above, a well positioned black light, and you have Ectoplasm Punch, a glowing green liquid that aliens, astronauts and Ghostbusters (sexy or just regular) will be all too happy to consume.

Given the kid-centered nature of Halloween and the growing number of adults who don’t drink alcohol, I would be remiss not to mention that yes — you absolutely can adapt this trick into a nonalcoholic treat. If you don’t have a preferred punch at the ready, my recommendation would be to doctor up a big can of pineapple juice with coconut cream and lime juice. Add a quarter cup of tonic water and a teaspoon of the liquid riboflavin. Stir them all together, and adjust to your preferred acidity and sweetness level by adding more lime or more coconut cream. Go ahead, and green it up further with food coloring, if you like. It’s not like Halloween is a health-food holiday.

Should you decide to take your spooky factor to the next level (you should be willing to commit to sobriety for the evening, because you’ll want to ensure safe handling!), you can use a pound or so of dry ice pellets. These should not go into the drink itself, but can go into a metal punch bowl with water and regular ice, creating a fog-emitting ice bath in which you can rest your pitcher of ghoulish goo. Note: Do not consume any beverage with dry ice in it.

Finally, a note on the drink: This is Halloween, an evening known for its high sugar content, and the Midori and coconut cream make for a drink that is definitely more on the “adult candy” side. Should your costume choice (or, er, natural state of being) be Snooty Mixologist, you might opt to sub all or half of the Midori for Chartreuse or another green herbal liqueur — either with the Midori or on its own, it slides nicely into this recipe, resulting in a cocktail that’s almost as green and much more complex. Whichever version you make, enjoy, and call me if your doorstep receives any sexy Labubus this year. I may know a sexy Wookiee who’s looking for a date.

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Ectoplasm Punch

3 cups white rum

1½ cups fresh lime juice (from 12 to 14 limes)

1½ cups Midori melon liqueur

½ cup cream of coconut, such as Reàl brand

½ teaspoon lime or lemon bitters (optional)

15 drops liquid vitamin B2 (riboflavin)*

Ice cubes or oblong ice block**

1 cup chilled tonic water

In a large bowl or pitcher, whisk or stir together the rum, lime juice, Midori, cream of coconut, bitters, if using, and vitamin B2, until the coconut cream is fully incorporated.

Fill a 2-quart, clear pitcher about one-quarter full of ice cubes or with an ice block. Add the rum mixture and stir, then top with the tonic water and stir gently to combine.

Serve under a black light into clear punch cups full of ice.

Servings: 12-14 (makes about 7 cups)

Total time: 10 minutes.

Variations: For a more sophisticated-tasting drink with herbal notes, replace the Midori with Chartreuse or other green herbal liqueur. The green color will be somewhat muted.

*Where to buy: Black lights can be found at party supply stores and online. Riboflavin (vitamin B2) drops can be found in vitamin shops and online. If you want to do the dry ice presentation, you can order it online, at specialty ice suppliers and at some supermarkets.

**Notes: To make an oblong ice block, fill a tall, narrow container, such as a highball glass with water and freeze until solid, 24 hours. To unmold, briefly run the bottom and sides of the glass under hot water, until the block of ice unmolds from the glass. For an additional theatrical touch, add ice cubes and a few cups of water to a punch bowl. Use rubber gloves or a spoon to add a few chips of dry ice to the bowl of ice water to create a spooky mist. (Do not handle dry ice bare-handed, and do not add dry ice to the pitcher or individual drinks.) Set the pitcher of punch inside the bowl and serve it from there.

Make ahead: If making an oblong ice block, you will need to freeze it 1 day in advance of making the drink. The punch can be mixed and refrigerated (without the tonic water) up to 1 day in advance; add the tonic water just before serving.

Nutritional information per serving (about ½ cup), based on 14: 225 calories, 1 g fat, 1 g saturated fat, 18 g carbohydrates, 7 mg sodium, 0 mg cholesterol, 0 g protein, 0 g fiber, 16 g sugar.

— M. Carrie Allan