In large bowl, beat egg whites with cream of tartar until soft peaks form. Beat in sugar 1 tbsp at a time until stiff glossy peaks form. Beat in vanilla. On foil-lined baking sheet, spread meringue into 10 inch circle, pushing up edge to form ring. Bake at 275 degrees for 1 1/2 hours or until firm to the touch. Turn off oven and leave meringue in oven to dry. Remove foil, then let cool and place meringue on serving platter. Just before serving, spread lemon cream sauce over meringue and cover with blueberries. Cut into wedges to serve.

Lemon Cream Sauce:
4 c low fat natural yogurt
1/3 c white sugar
2 tbsp lemon juice
grated rind of one lemon

In cheesecloth-lined sieve set over bowl, cover yogurt and let drain in refrigerator for at least 4 hours or overnight or until yogurt is about 2 c or less. Discard liquid. In bowl, stir together drained yogurt, sugar, lemon juice and rind. Refrigerate up to 2 days.