Step 1

Preheat oven to 425°F. In a medium saucepan combine sugar, water and cream of tartar, whisking until sugar has dissolved. Bring mixture to boil over high heat, whisking occasionally, then reduce heat to medium. Simmer for 15 minutes or until mixture has reduced to 1 1/2 cups. Stir in zest, juice and vanilla. Set aside to cool for 30 minutes.

Step 2

Roll out crusts. For a nine inch pan your bottom crust should be around 11 inches in diameter, your top crust, about 10 inches. Place bottom crust in pie pan or dish. Add crumbled crackers. Pour syrup over crackers and dot with pieces of butter then sprinkle evenly with cinnamon.

Step 3

Beat together egg and milk. Place top crust over pie. Seal and flute the edges and brush with egg wash then sprinkle with sugar. Cut several small slits into the top crust to vent the steam. Bake for 30 minutes or until golden brown. Cool and serve. Store covered.