Toasted Ciabatta with Balsamic Syrup

From Everyday Pasta - Giada DeLaurentiis

1 1/2 C balsamic vinegar
4 Tbsp sugar
12 1/2" thick slices ciabatta bread
2 Tbsp unsalted butter, softened

Boil the balsamic vinegar and 3 tablespoons of sugar in a small, heavy saucepan over medium-high heat until reduced to 1/2 cup, stirring occasionally, about 20 minutes.
Toast the bread slices. Spread the butter over the toasts. Arrange the toasts on a platter. Drizzle the reduced balsamic syrup over the toasts, then sprinkle with the remaining sugar, and serve.