Start by steaming the pumpkin for 15 minutes at 100 degrees with 100% humidity. This step makes the baking much faster and also makes it much easier to empty the pumpkin.
In a pan, add the olive oil and heat up. Add onions and garlic and fry for 4 minutes. Add the herbs and mushrooms, cook for 5 minutes and deglaze with white wine. Continue cooking until the mushroom have reduced for around 12-15 minutes. Add walnuts and chickpeas (quinoa or chopped chestnuts) and cook another 5 minutes. Season with salt and pepper.
After the pumpkin steaming is done, cut the top (around 5 cm from the top) and remove the seeds inside. Fill with the mushroom stuffing you just prepared, add the pumpkin lid and brush the outside with olive oil. Transfer to a tray and cook at 180 degrees for 30-40 minutes. It should be soft and golden. If you have more stuffing than what fits in the pumpkin, add to a different tray, cover it and cook simultaneously as the pumpkin.
Remove from the oven and cool for 10 minutes before serving.