Heat oven to 350 degrees F. In a medium saucepan combine sugar, butter, molasses, zest, ginger, and cinnamon over medium heat. Bring to a boil and remove from heat. Whisk in flour. Add cognac and whisk until smooth.
Drop batter, 1 heaping tablespoon at a time, onto a baking sheet lined with a silpat or parchment. Prepare only 2 cookies at a time because they harden quickly once removed from the oven and are difficult to shape.
Bake for 10 to 12 minutes. Remove and let cool for 3 minutes. Run a thin spatula all around the perimeter of 1 snap at a time to loosen the bottom completely. Quickly place the snap, flat side up, over the bottom of a custard cup, about 3 inches in diameter and 2 1/2 inches deep. Let cool. (If the snap becomes hard before removing from baking sheet, return briefly to the oven.)
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