For the syrup: In a small saucepan over medium heat, combine the water, sugar, ginger, cinnamon, and cloves. Bring to a boil, then reduce the heat and simmer for 5 minutes, stirring occasionally, until the sugar has dissolved.
Remove the pan from the heat and allow the syrup to cool, about 20 minutes.
Remove and discard the ginger, cinnamon, and cloves.
For the espresso: In an 8-ounce glass measuring cup, whisk together the boiling water, espresso powder, and liqueur, if using, until the powder is dissolved. Set aside to cool.
Combine 1 cup syrup with the espresso/hazelnut liqueur mixture in a large martini shaker.
