Stir with ice, strain into a cocktail coupe, and garnish with a lemon twist.
The sweetness and flavor intensity of the orgeat will dictate whether the orgeat volume should be dropped to 3/8 oz or 1/4 oz. With homemade orgeat, I enjoyed it at 1/2 oz.
In thinking about the Manhattan-like recipes from Pioneers of Mixing at Elite Bars: 1903-1933 that contain orgeat (see source reference for links), I decided to take the idea and include in elements from the 1919 and Japanese Cocktails. With a split base of Cognac from the Japanese and rum from the 1919, I opted for Jamaican rum to provide some funk and dryness to the mix. For a name, I dubbed this one the 1790 -- the year that the tropical almond tree was introduced to Jamaica.