Prepare a 6-serving stove-top espresso maker according to manufacturer's directions and brew a pot of espresso. Put the sugar in a large glass measuring cup and add 1 tablespoon of the hot espresso. Using a small whisk, beat the sugar with the espresso until pale and thick and nearly dissolved, about 1 minute. Stir in the remaining hot espresso. Let the foam rise to the top, then pour into espresso cups and serve immediately.