Beat the 12 eggs, 2 cups sugar and vanilla essence together. Stir in the ricotta cheese and the chocolate chips. Set aside.
Preheat oven to 170 degrees C. Grease two deep dish pie tins.
Combine the flour, baking powder and 1 cup of the sugar together. Cut in the butter and mix until the mixture resembles coarse crumbs. Mix in 4 eggs and 1 teaspoon of the vanilla. Divide dough into 4 balls and chill (if needed).
Roll out 2 of the balls to fit into the pie tins. Do not make the crust too thick as it will expand during cooking and get too thick. Do not flute the edges of the dough. Roll out the other 2 balls of dough and cut each into 8 narrow strips for the top of the crust. Alternately you can use biscuit cutters and place the cutouts on the top of the pies.
Pour the filling evenly into the pie shells. Top each pie with 8 narrow strips of dough or biscuit cut-outs. Brush top of pie with milk. Cover with foil.
Bake at 170 degrees C for 20 to 30 minutes then remove foil. Continue to bake for another 25 or 30 minutes or until a knife inserted in the centre comes out clean.