Half all the tomatoes and add to a roasting tray with the garlic, fine chopped basil stalks and the red onions. Sprinkle with a pinch of salt, pepper and the caster sugar and some olive oil and roast in the oven for 20 minutes until the tomatoes are soft but not coloured.
Meanwhile hollow out the middle of the loaf of bread. Remove the tomatoes from the tray and place in a blender with the softened onions and basil stalks. Squeeze the soft middle from the garlic from the bulb and add too.
Blitz until smooth. Add to a pan on a low heat and season to taste. Serve through the stock and cream and pour in the bread bowl.