In a small saucepan over medium heat, combine the butter, brown sugar, sage, granulated onion, maple syrup, salt, and pepper and cook until melted. Brush the butter mixture all over the exposed flesh of each squash. Grill, cut sides up, over Indirect Medium heat for 30 minutes. Sprinkle the cheese and parsley all over the exposed flesh of each squash. Continue to grill until the flesh is very soft when pierced with the tip of a knife and the cheese has browned, 20 to 30 minutes more. Serve warm.