Hands On: 45 minutes
Total time: 2 hours, including chilling & baking time
For the pastry:
1 C (2 sticks) unsalted butter, at room temperature
1/2 C granulated sugar
1 egg
1/2 tsp vanilla extract
2 3/4 C all purpose flour
1/4 tsp salt
For the filling:
1 C granulated sugar
3 T cornstartch
2 T lemon juice
3 C fresh or frozen blueberries
Confectioner's sugar, optional
For the pastry: In a mixing bowl, beat together the butter and sugar until fluffy. Beat in egg and vanilla. Stir together the flour and salt, then beat into butter mixture until just combines. Scrape onto a a sheet of plastic wrap. Form into a ball and wrap in the plastic. Chill 1 hour (don't over chill or it will be difficult to roll out!)
For the filling: In a saucepan, combine the sugar and cornstarch. Stir until no lumps remain. Add the lemon juice and blueberries and cook over medium heat, stirring constantly until all of the sugar is incorporated into the liquid, about 4 minutes. Increase heat to medium-high and cook, stirring constantly, until mixture boils and thickens, about 5 minutes. Remove from the heat and set aside.
Preheat oven to 350 degrees. Butter the bottom of a 9 x 13" pan or baking dish. Press half the pastry into the bottom and 1/2" up the sides of the pan. Place the pan in the refrigerator.
Roll out the remaining dough between 2 sheets of wax or parchment paper. Using a flute pastry wheel or a knife, cut the dough into 1/2" wide stripes. Slide the dough and wax paper onta a cookie sheet and place in the refrigerator or freezer for a few minutes. Meanwhile, spread the blueberry filling over the bottom crust. Arrange the pastry strips in a lattice pattern over the filling - no need to interweave them, though. If the strips break, just overlap the edges slightly; they'll bake together.
Bake for 30-35 minutes, until pastry is lightly browned. Remove from the oven and cool for 30 minutes before cutting into squares. Sprinkle the tops with confectioner's sugar, if desired.
