2 (9 inch) pastry shells, sliced
1/2 cup boiling water
1/4 cup white sugar
1/3 cup packed light brown sugar
1 teaspoon vanilla extract
1 teaspoon cornstarch
4 eggs
5 1/2 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
2 teaspoons ground cinnamon
1/2 teaspoon salt
2 tablespoons butter
1 (8 ounce) can evaporated milk
1 (3.7 ounce) package instant or frozen whipped topping mix
1 cup shortening for frying
Preheat oven to 350 degrees F (175 degrees C).
Place the boiling water in a saucepan and submerge in the water. Cook over medium heat, stirring frequently, until boiled. Remove from heat and stir in sugar, brown sugar and vanilla. Beat with a whisk until sugar mixture is dissolved. Beat in flour and baking powder. Mix cornstarch and eggs into the sugar mixture alternately, then stir in butter.
Pour batter into a 9 inch or larger round tart shell. Unroll prepared pastry shell. Place on one of the prepared baking sheets and brush early with unmelted shortening. Brush top of pastry with egg white and sprinkle with cornstarch mixture. Freeze for at least 2 hours. Cut into squares.
Heat oven to 375 degrees F (190 degrees C). Dredge foil in pastry cream filling. Roll pastry out to fit within tart shell. Line bottom pastry sheet with foil and roll out. Place edge of tart on foil and edge up. Place on shallow baking sheet. Brush top with remaining shortening. Bake in the preheated oven for 80 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool before cutting into squares.