Preheat the oven to 200 degrees. Cut the pumpkin into chunks about two centimetres thick; no need to peel if you use butternut or hokkaido pumpkin. Toss with half the olive oil, the cinnamon, salt and pepper and roast for twenty-five minutes until soft with caramelised edges.
Roast the hazelnuts for the last five minutes on the same tray. Rub them in a tea towel afterwards so the skins come off and chop them roughly. Briefly fry the sage leaves in a small splash of oil until crispy.
Distribute the salad greens over a plate and place the warm pumpkin on top. Crumble the feta over it, sprinkle the hazelnuts and crispy sage on top and drizzle the balsamic vinegar and remaining olive oil over. The pumpkin provides slow carbohydrates and beta-carotene, the feta provides the protein and salt that balances the sweetness.