COOK IT.
Preheat barbecue to MEDIUM. Spray a large piece of aluminium foil with vegetable oil spray. Lining the foil with parchment first will prevent the vegetables from sticking. Place parsnip, carrot, sweet potato, corn, garlic and onion in the middle of the foil, and toss with olive oil and apple cider. Fold foil into a pouch. Place on grids, reduce heat to MEDIUM/LOW and cook for 35 minutes. Remove from heat and set aside.
Cut the Acorn squash in half lengthwise and remove seeds. Rub inside with butter, season with salt and pepper. Place on grids, skin down, and cook for 35 minutes, until tender If serving immediately: Assemble stuffed acorn squash by placing a scoop of stuffing into each acorn squash half, and top with pumpkin seeds and maple syrup.
If serving the next day: Store covered, in the refrigerator. Assemble stuffed acorn squash by placing a scoop of stuffing into each half of acorn squash and reheat on the barbecue for 20 minutes on MEDIUM. Top with pumpkin seeds and drizzle with maple syrup before serving.