Preheat oven to 325˚F and lightly grease a 9 inch round pan with removable bottom.
On a floured work surface, roll the larger piece of dough into a 1/8 inch thick circle. Gently place in the 9 inch pan, using your fingers to press the crust to fit into the bottom of the pan. Fold the top of the crust over the edges of the pan.
Pour the filling into the crust, using a spatula to evenly distribute.
On a floured surface, roll the second piece of dough into a 1/8 inch thick circle. Cut into 1/2 inch wide strips. Place the strips over the filling in a lattice pattern. Neatly fold in the edges of the bottom crust, cutting away any excess.
Brush the crust with the beaten egg. Bake in preheated oven until the filling sets and the crust turns golden brown, about 1 hour. Let cool in pan 15 minutes before removing to wire rack. Refrigerate when cool. Serve chilled, dusted with additional ground cinnamon if desired.