COMBINE strawberries, blueberries and 3 tablespoons granulated sugar in large bowl; stir gently. Let stand, stirring occasionally, for 30 minutes.
PREHEAT oven to 425° F. Spray baking sheet with nonstick cooking spray.
WHISK flour, remaining 4 tablespoons granulated sugar, baking powder and salt in large bowl; cut in butter with pastry blender or two knives until mixture resembles coarse crumbs. Add milk and yogurt; stir just until a moist dough forms. Turn the dough onto a floured work surface. With floured hands, knead 6 to 8 times until the dough is smooth. With rolling pin, roll dough into a 9 x 6-inch rectangle or until about ½-inch thick. Cut into six 2 ½-inch circles. Transfer to prepared baking sheet. Sprinkle with sparkling sugar.
BAKE for 10 to 12 minutes or just until golden. Transfer biscuits to individual plates; split open. Top each with about 1 cup berry mixture and ½ cup vanilla ice cream.
Cook's Tip: If you have a little remaining dough, pat back into a ball, flatten slightly and cut into circles.