Meanwhile, COMBINE egg yolks, remaining sugar, lemon juice, and lemon zest in top of a double boiler.
COOK until thick; REMOVE from stove and allow to COOL.
WHIP the cream with the confectioners' sugar.
BLEND half the whipped cream with the lemon mixture and SPREAD into cooled meringue shell.
TOP with remaining whipped cream.
REFRIGERATE 24 hours before serving.
SEPARATE eggs; RESERVE yolks.
BEAT egg whites until frothy.
ADD cream of tartar and beat until soft peaks form.
Gradually ADD sugar, beating until egg whites are stiff and glossy.
GREASE a 9 1/2-inch glass pie plate with butter; carefully SPREAD beaten egg whites, including mounding along edge of dish.
BAKE in a 250° oven for 90 minutes; TURN OFF oven; leave shell in oven 1 hour.
May substitute Kool Whip
Per Serving (excluding unknown items): 248 Calories; 16g Fat (58.3% calories from fat); 3g Protein; 24g Carbohydrate; trace Dietary Fiber; 125mg Cholesterol; 31mg Sodium. Exchanges: 0 Lean Meat; 0 Fruit; 0 Non-Fat Milk; 3 Fat; 1 1/2 Other Carbohydrates.