Cut the unpeeled pumpkin into wedges (1-2cm at the thick end) and discard the seeds; leave the skin on;
In a large bowl, toss the pumpkin pieces with 5 tbsp of olive oil, the cinnamon, 4 tbsp of honey, the garlic, sage, half the bay leaves, and salt and pepper;
Lay out in a single layer in a large roasting tray and roast for 20-25 minutes, until the pumpkin is soft and golden;
Add the chestnuts 5 minutes before the end.
Arrange the tray's contents on a serving platter and scatter the remaining bay leaves over the top;
Stir together the remaining syrup and oil, and drizzle on top;