Blueberry Lemon Poppy Seed Pie

To make the streusel, whisk together all ingredients except for the butter in a small bowl. Use your hands or a pastry blender to rub the butter into the mixture until you have something that resembles coarse crumbs.
Store in the refrigerator while you work on the rest of the pie.
Par-bake your pie: Preheat the oven to 400u0b0 F. Roll the dough out (once your dough is nearly rolled out, you can scatter poppy seeds across and press them gently in, if you'd like!). Place it in the dish, crimp the outside, and freeze for at least 30 minutes (and up to 3 days). Line the crust with parchment, fill it with pie weight, dried beans, or rice, then bake for 10 minutes. Remove weights and parchment and continue to bake for 5 to 8 minutes, until a pale golden brown. Transfer to a write rack to cool slightly. Lower the oven temperature to 375u0b0 F.
Meanwhile, make the filling. Gently mix the blueberries with sugar, salt, cornstarch, and lemon zest. Set aside for 10 to 15 minutes.
Spread 2 tablespoons of the creme fraiche over the bottom of the pie crust; sprinkle with one-third of the chilled streusel. Arrange blueberries on top, dot with remaining 3 tablespoons of creme fraiche. Sprinkle with remaining streusel.
Bake until creme fraiche is bubbling and streusel is golden-brown, about 50 minutes. If the crust is browning too quickly, cover it with foil. Let cool on wire rack for at least 30 minutes. Serve garnished with whipped cream and more lemon zest.