Crumble the blue cheese with a fork in a bowl. Add the creme fraiche or cream and beat with a hand mixer to make a smooth mousse. Stir in the chopped walnuts
Sprinkle the diced pears with the lemon juice.
Layer the glasses starting with the pears, and topping with the cheese. Decorate each with a walnut half. Refrigerate, but remove from refrigerator about 1/2 hour before serving to fully appreciate.
Makes 12 servings.