Pair two of the best things about summer: fresh blueberries and ice cream. Make a sauce by melting 2 teaspoons unsalted butter in a saucepan set over medium heat; then add 1 pint blueberries and 1/4 cup sugar. Cook, stirring, until blueberries release juices, about 2 minutes. Cool slightly, and spoon warm sauce over ice cream. Garnish with more blueberries, if desired. Makes 1 1/3 cups.