Trinidad sour 👍
Recipe
4 parts Angostura bitters
4 parts waldmeister syrup (or another syrup)
3 parts lemon juice
2 parts rye whiskey
Shake thoroughly and strain into a cocktail glass. (Yes, you read that right. Nearly a third of this drink is bitters.)
Normally bitters are something you put two or three drops of in a drink, and even then you run the risk of overpowering the other ingredients. It's such a strong flavour, with such an intense aromatic smell, that I wouldn't have believed this would work.
But it does. The main flavour is bitters, obviously, but there's enough sweetness and sourness to make it quite well balanced and drinkable. Bitters, consumed in these quantities, tastes of warm Christmassy spices and herbal remedies. It's actually a great taste, and I'm glad someone else did the experiment rather than leaving it to me to waste half a bottle of bitters for something that might be awful.
Note that bitters, which I've included in several recipes marked "non-alcoholic", is actually 45% alcohol. If it's only a few drops it's insignificant, but in this case it's more than a shot of vodka.