Cut the squash in half lengthwise. Line a baking sheet with foil. Brush the cut side with olive oil and place, cut side down, on the baking sheet. Place in a preheated 375-degree oven for an hour or until fork tender. Cool and scoop out the seeds. Remove the pulp and reserve. In a large heavy pot melt the butter and heat the oil. Add the onions and sauté for 5 minutes or until tender. Stir in the ginger, pepper, salt and sugar. Make a bouquet garnish from the thyme and bay leaf and add to the pot along with the stock. Bring to a boil Add the squash and cook for 15 minutes. Remove the bouquet garni and purée the mixture. Return to the pot and whisk in the light cream. Reheat, but do not allow to boil. Serve hot topped with a dollop of crème fraiche topped with a small spoonful of the chopped hazelnuts. Serves 8-10.