Preheat oven to 200C/390F.
Place the pumpkin, pumpkin seeds, onion and walnuts onto a large baking tray. Drizzle with olive oil and maple syrup, then use an egg flip to toss the pumpkin so it is evenly coated.
1. You can use whatever nuts you prefer but just be aware that you might need to adjust the cooking time i.e. toss them in partway through roasting. Walnuts hold up well in the oven for the full roasting time. Almonds, peanuts and cashews will also be fine for the full time. If using pine nuts, sunflower seeds or pepitas (or other small nuts), add them halfway through the roasting time.
2. If you use brown sugar instead of honey or maple syrup, mix it with the olive oil before pouring over the pumpkin.
3. Nutrition assuming 6 servings.