Cut pumpkin in half and scrape out seeds. Brush pumpkin inside and out with olive oil and place with cut side down onto a deep baking dish. Add unpeeled garlic and roast for 30 minutes in the preheated oven until the pumpkin is soft.
In the meantime heat 50ml olive oil in a pan and fry the sage leaves for about 1 minute. Set aside.
In the same pan saute onions, chopped sage, thyme and parsley for 12 minutes at medium heat until the onions begin to brown.
Scrape out pumpkin flesh from roasted pumpkin and remove skin from garlic. Place pumpkin, peeled garlic and all juices from baking dish with water or stock and salt into a large pot. Add onion mixture and simmer for 25 minutes halfway covered.
Finely puree soup (if soup is too thick, add more liquid). Season with salt and pepper and serve with fried sage leaves.