In a large glass bowl, beat egg whites and cream of tartar until foamy. Add in sugar a little at a time and continue beating until stiff and glossy. Lastly, beat in vanilla. **Do not under-beat**
Assembly:
Pour hot filling into baked crust and top with meringue, making sure to push meringue all the way to the edges of the crust so it doesn't shrink during baking/cooling. Bake at 350 degrees for about 10 to 12 minutes or until golden brown. Cool before eating.