Used for brushing the génoise cake for the Bûche de Noël.
Adapted from Jacques Torres’ “A Year in Chocolate."
In a small, heavy-bottomed saucepan, combine the water and sugar, place over medium-high heat, and bring to a boil, stirring occasionally. When the sugar has dissolved completely, remove the pan from the heat. Transfer to a heatproof bowl and let cool completely.
Stir the liqueur into the cooled syrup. Use immediately, or store, tightly covered, in the refrigerator almost indefinitely.