On the cocktail menu at Saul in New York City is this wonderful Scotch-based drink featuring housemade Saigon cinnamon and walnut bitters.
In a large shaker tin, combine Scotch, Drambuie, lemon juice, chestnut-honey simple syrup (mix 2 parts hot water with one part chestnut-honey), 5 small-medium sage leaves, and 4-5 drops of bitters, with large-format ice and shake vigorously for a least 10 seconds.
Double strain into a double old-fashioned glass filled with ice (for an interesting riff on a Whiskey Smash, use crushed ice and garnish with a tuft of sage). Garnish with one sage leaf and add 4-5 more drops of bitters.
Bring the cocktail up to your nose, sip, close your eyes and notice clear distinctions in the succession of tart, smoky, sweet, nutty, and bitter flavors.