Apricot-Nectarine Julep

Preheat oven to 400°F. Toss together apricots, nectarines, and sugar on a large rimmed baking sheet until fully coated; spread in an even layer. Roast in preheated oven until fruit is soft and juicy, about 20 minutes, stirring halfway through roasting time. Let cool 5 minutes. Scrape fruit and any liquid on baking sheet into a food processor or blender; pulse until smooth, 5 to 8 pulses. Pour through a fine wire-mesh strainer into a medium bowl. Refrigerate, uncovered, until completely cool, about 20 minutes. (You should have about 2 cups apricot-nectarine puree, enough for 8 cocktails.)

Muddle mint leaves and 1/4 cup apricot-nectarine puree in bottom of a julep cup. Add bourbon and crushed or pebbled ice to cover; stir until chilled, about 20 seconds. Fill cup with additional ice, adding enough to form a small mound on top. Pour 2 to 4 tablespoons apricot-nectarine puree over ice. Garnish with a mint sprig, and serve with a short julep straw.