You can use either fresh or frozen blueberries in this recipe. I think the combination of tapioca and corn starch insures that the filling will thicken to just the right consistency.
1 1/2 cups sugar
1/4 cup quick-cooking tapioca
2 Tbsp cornstarch
6 cups blueberries
1 tsp lemon juice
1 box refrigerated pie crust, 2 crusts
1 extra large egg white, lightly beaten
1 Tbsp butter
1 tsp milk
1/2 tsp sugar
1. In a large bowl, combine the sugar, tapioca, and cornstarch. Toss in the blueberries and lemon juice. Let stand 15 minutes.
2. Place a foil lined baking sheet on the middle rack of the oven and preheat to 450°.
3. On a lightly floured board, roll one of the pie crusts into a 12″ circle then fit into a 9″ pie pan, allowing the edges to overlap the sides. Brush the bottom and sides with the egg white, reserving any remaining egg white.
4. Give the blueberry mixture another toss and pour into the prepared crust. Spread the blueberries and any of the unincorporated sugar mixture evenly. Dot the filling with butter.
5. Center the remaining crust over the filling. Fold the overhanging to crust under the bottom crust and crimp to seal. With a sharp knife, cut several slits in the crust.
6. Beat together the remaining egg white and milk and brush this mixture over the top crust and sprinkle with sugar.
7. Place the pie on the hot baking sheet and reduce the oven temperature to 400°. Bake 25 minutes.
8. After the first 25 minutes, shield the edges of the crust with aluminum foil to prevent burning. Bake the pie for another 40 minutes or until the filling is bubbling thickly.
9. Let cool before cutting.