1 (9 inch) unbaked pie crust
3/4 cup white sugar
1/3 cup all-purpose flour
2 teaspoons grated lemon zest
1 tablespoon lemon juice
5 cups fresh or frozen blueberries
2/3 cup packed brown sugar
3/4 cup rolled oats
1/2 cup all-purpose flour
1/2 teaspoon ground cinnamon
6 tablespoons butter
Preheat the oven to 375 degrees F (190 degrees C).
Press the pie crust into the bottom and up the sides of a 9 inch pie plate. In a large bowl, stir together the sugar and flour. Mix in the lemon zest and lemon juice. Gently stir in the blueberries. Pour into the pie crust.
In a medium bowl, stir together the brown sugar, oats, flour and cinnamon. Mix in butter using a fork until crumbly. Spread the crumb topping evenly over the pie filling.
Bake for 40 minutes in the preheated oven, or until browned on top. Cool over a wire rack.