Set the oven's temperature to 200°C/400°F. Scrape the seeds out after cutting the butternut squash in half vertically. Apply a thin layer of olive oil to the interior of each squash half and rub it into the meat. On a roasting pan, place the squash face down. Bake for 45 minutes, or until the skin is blistered and the interior is soft.

The zucchini should be taken out of the oven and left to cool for ten minutes. In the meantime, add the butter and olive oil to a big soup pot and cook it up on medium. Add the onion and garlic to the saucepan after roughly chopping them. Sprinkle the nigella seeds, salt, and plenty of freshly ground pepper over the onion and simmer for 5 minutes, or until the onion has softened.

Cut the squash into cubes once it is cool enough to manage, then add to the pot. Add the stock, then simmer for an additional 10 to 15 minutes.

Transfer to a food processor or blender, and puree until smooth. In order to store, go back to the saucepan or another container. Immediately serve steaming. If desired, add a dollop of crème fraîche or sour cream.