Preheat oven to 250 F (120°C). Line a cookie sheet with foil. Draw a 9 inch (23 cm) circle on it.
In a large glass or metal bowl, beat egg whites, vanilla, cream of tartar and salt at highest speed of electric mixer until soft peaks form.
Gradually beat in 1 cup sugar, 2 tbsp at a time, beating until stiff, glossy peaks form. Spoon onto prepared cookie sheet within the circle, with eggs piled higher than center.
Bake for 1-1/4 to 1-1/2 hours until crisp on the outside and firm to the touch. Turn off heat and allow to cool in oven with oven door propped open.
Meanwhile, in a heavy saucepan, whisk together egg yolks, remaining 1/3 cup (75 mL) sugar and lemon juice.
Cook over low heat, stirring constantly, 5 to 6 minutes or until thickened and smooth. Cover surface directly with plastic wrap; cool.
Whip cream until stiff; fold in cooled lemon mixture. Just before serving, spread whipped cream mixture over meringue.