Coat both sides of naan with cooking spray. Add naan to grill; grill 2 minutes on one side. Remove from grill; spread the ricotta mixture evenly over the grilled side of naan. Top with tomato and peach slices. Place flatbreads on grill; grill 3 minutes. Sprinkle with remaining 1 tablespoon onions, basil, and salt. Cut each flatbread into 8 wedges.