Wash the hearts of the lettuce. Drain of water and cut into four pieces, lengthwise. Arrange on a serving dish. Then, place gorgonzola in a metal bowl and use the tongs of a fork to break it apart. Add the cream, and slowly incorporate the oil. Whisk the mixture as if you were making mayonnaise. Drizzle with the vinegar (or lemon juice) and sprinkle with finely chopped chervil. Adjust the salt and pepper and serve the lettuce with this flavorful sauce.