Cook sown the cream in a small, heavy saucepan over med. Heat until reduced by about a third. Set aside. Heat a heavy cast-iron griddle or skillet over high heat until a drop of water sizzles on contact. Roast the unpeeled garlic cloves and onion, turning several times, until the garlic is dark on all sides and somewhat softened and the onion is partly blackened and fragrant. Set aside. Roast the tomatoes in the same way, turning several times, until blistered on all sides. Let cool until cook enough to handle. Peel the garlic and place in blender. Peel onion, and add to garlic. Peel tomatoes directly over the blender to catch juice. And add to garlic and onion. Puree on medium speed until smooth. Add the cream and process until blended. Season with salt. Makes about 4 cups. Can be refrigerated for 2 or 3 days. Do not freeze.