In a cocktail glass, combine ice, cherry juice and magnesium powder.
Shake for 10-15 seconds until well-chilled.
Pour the mixture into a wine glass or a cocktail glass of choice.
Top with bubbly prebiotic soda or a seltzer like La Croix.
Notes
A little chalky? I liked my drink, but I do think that 1 teaspoon of powder is the maximum. Try it with half a teaspoon if you find it a little too chalky.
Too much flavor? After trying it with the specific ingredients above (all of which I already had on hand), I would probably prefer an unflavored magnesium powder. I honestly think I just don't love the berry flavor that the Moon Juice brand comes in and maybe others would.
Additions - I think a squeeze of lime juice could be a nice addition against the tart cherry juice. I also think experimenting with different flavored sodas is a good idea to find the flavor combination you enjoy most.
Substitutions - If you don't love the tart cherry juice, try cutting it with more soda water or prebiotic soda. If you don't like the magnesium powder, you can easily omit it and use a magnesium spray or take another supplement (such as a pill). I love the prebiotic sodas and find them to be a nice mocktail on their own, or added to a recipe like this. Bottom line, any combination of these ingredients may make a great mocktail for your bedtime routine, so feel free to tweak it to your tastes.