Based on the Cynar Toronto from Serious Eats (https://www.seriouseats.com/recipes/2013/04/cynar-toronto-easy-rye-cocktail-recipe.html) we found that it was a bit too bitter for our tastes, so we added a little limoncello to brighten and sweeten it up.
2 oz rye or bourbon (we used Bulleit)
3/4 oz Cynar
1 - 2 tsp (to taste) Limoncello
1 tsp simple syrup (1:1 by mass)
2 dashes Angostura
Instead of serving in a coupe glass, our party prefers to serve (even shaken) cocktails on the rocks.
For this, one king cube in a rocks glass. Put dashes of Angostura (or other orange/flask bitters) on king cube.
Put all other ingredients in the shaker, with ice. Shake hard until the shaker is frozen in your hands. Single or double strain into rocks glass on top of the cube.