1Heat gas or charcoal grill. Tear off 12-inch length of heavy-duty foil to make packet. Lightly spray 1 side of foil (side that will be inside of packet) with canola oil cooking spray.
2In small bowl, stir together butter, 1/2 teaspoon sugar, the cinnamon and salt; set aside.
3In another small bowl, toss blueberries with 1 to 2 tablespoons sugar and the cornstarch to coat. Place berries in center of spray side of foil; top with granola and butter mixture. Bring up 2 sides of foil so edges meet. Seal edges, making tight 1/2-inch fold; fold again, allowing space on sides for heat circulation and expansion. Fold other sides to seal.
4Place foil packet on grill. Cover grill; cook 8 to 10 minutes, turning packet once, until berries burst and butter melts. Cooking times are approximate and depend on the heat of your grill. Serve with ice cream.