4 ounces unflavored gelatin 1/4 cup sugar 1 cup cold water 1 cup boiling water 12-ounce can frozen berry blend juice concentrate, thawed 2 cups heavy cream 1/4 cup powdered sugar 2 pounds fresh strawberries, quartered 13-ounce angel food cake, cut into cubes Lightly coat a 9-by-13-inch baking pan with cooking spray, then line it with plastic wrap, leaving excess wrap overhanging the short ends of the pan. In a medium bowl, stir together the gelatin, sugar and cold water. Let sit for 5 minutes.