FILLING
8 egg yolks
4 oz. flour (should be weighed almost 1 c.)
6 oz. sugar (a little over 1 c.)
1 qt. of milk
1/2 tsp. cinnamon
4 tbsp. cocoa
1 lemon rind

Beat eggs, add flour, sugar and milk.  
In saucepan cook mixture as you would 
pudding, stirring constantly with lemon rind.  
When thickened divide in half and add cocoa to 
1/2 and vanilla and cinnamon to other half.  
Set aside to cool (throw away rind). 

CRUST
2 egg yolks
2 c. flour
2 tbsp. sugar
Pinch of salt
1/2 c. shortening
1/2 tsp. vanilla
Pinch of baking powder

Sift flour, salt, baking powder and sugar together. Add egg yolks and cut in shortening and vanilla. if too dry add a bit of milk. Divide dough for upper and lower crust into 2 balls. Roll out on floured board. Put bottom crust in greased deep 10 inch pie plate (or larger). When filling is cool, pour in vanilla then chocolate on top. Do not mix. Put on top crust. Bake in 300 degree oven 45 minutes to 1 hour. A rich dessert serve small pieces as you would cheesecake.
 

Source: http://www.nancys-kitchen.com