For the soup, wash the pumpkin, quarter it and remove the seeds. Cut the flesh and skin into small pieces. Peel onions and garlic, dice both.
Heat the oil in a pot. Fry the pumpkin, onions and garlic in it. Season with salt, pepper and 1⁄2 tablespoons of sugar. Add vinegar, tomatoes and juice, about 1 l water and broth. Mash the tomatoes with a wooden spoon.
Bring to the boil, cover and cook for about 30 minutes.
Preheat the oven for the pesto ciabatta (electric cooker: 150 °C/circulating air: 125 °C/gas: see manufacturer). Cut the ciabatta lengthwise, but not through. Mix pesto with butter. Spread on one half of the bread, fold up and bake in the oven for 5-10 minutes.
Puree the soup with a hand blender. Season to taste with salt and pepper. Whip cream until semi-stiff and serve with bread to the soup.