When I think of creme de menthe, I remember holidays at my cousins' house, where we'd put the bright green liquid on vanilla ice cream during the holidays. I didn't really like the taste of it that much, but I liked the visual effect. I guess I've always been a fan of dramatic garnish.
Other people probably remember creme de menthe better for the cocktails that called for it, like the Grasshopper and the Stinger. As I became more familiar with classic cocktails years ago I gave these a try, but found them to be generally quite awful.
Creme de menthe is a liqueur that can be clear or green but typically tastes like mint and sugar, kind of like liquid mint gum. It serves the purpose of being minty and that's about it.
Now, however, there is a newish brand called Tempus Fugit Creme de Menthe Glaciale that was recreated from a recipe from the 1800s and made with real mint and other ingredients. It's clear and has an icy tingle to it, and is so refreshing that you can enjoy it on its own as a digestif.
After trying the new liqueur, I went back to those old recipes to give them another chance. It turns out they can be quite fantastic. It wasn't the fault of the recipe, but of the ingredients I had been using.
3 fl. oz. Cognac
1 fl. oz. Tempus Fugit Creme de Menthe Glaciale
Stir with ice and strain into a cocktail glass.
You might also want to reconsider the Grasshopper. It uses cream, creme de menthe, and creme de cacao- another ingredient that is typically one-dimensional and artificial tasting. But luckily, Tempus Fugit makes a delicious version of that as well.