Traditional South African Melk Tert

I've made a melktert before, with my Culinary Arts class during our African foods unit. Here's a slightly different version (traditional family recipe) with what is probably a more authentic crust -- which is not actually a crust at all.

Filling Ingredients
3 T cake flour
4 T cornstarch
1 C sugar
1 liter milk
125 grams butter
4 eggs
1 T vanilla
          cinnamon

Crust Ingredients
2 T butter
2 T sugar
1 egg
3 T flour
1 tsp baking powder

Directions
Preheat oven to 400.

Begin Filling: In a large saucepan, mix cornstarch, flour and sugar. Slowly add in milk, stirring to combine dry ingredients smoothly. Bring slowly to a boil, stirring constantly until it just begins to boil, and thickens. Add butter, stirring until butter melts; stir in vanilla. Set aside to cool while preparing crust.

Prepare Crust: Cream together butter and sugar. Blend in egg. Stir in flour and baking powder. Smear evenly over bottom and up sides of a pie pan.

Complete Filling: Whisk egg whites into stiff peaks. Stir half the egg whites into filling; gently fold in the remaining egg whites. Pour filling onto pie pan; sprinkle with cinnamon.

Bake 15-20 minutes; center will still be slightly 'loose' (jiggly) in the center.