Stir the sugar and water in a small saucepan over medium heat until the sugar dissolves, about 5 minutes. Cool the sugar syrup completely.
Fill 6 (8 to 12-ounce) glasses halfway with crushed ice. Pour the espresso over the ice, dividing equally. Pour 1 tablespoon of the sugar syrup and 1 tablespoon of amaretto into each glass. Stir to blend. Pour the milk into each and serve.