Here's a pie that's creamier, crunchier, and zingier than most blueberry pies get. The cream comes from crème fraîche, which is spread over the bottom of the par-baked dough and dotted across the top of the pie; as the pie bakes, it will bubble into a tangy, light custard.
The crunch comes from a poppy seed streusel that's scattered above and below the blueberry filling (if you'd like, you can add a scattering of poppy seeds to the dough itself, too). And the zing comes from a generous amount of lemon zest in the filling and as garnish.
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.
For the pie:
Par-bake your pie: Preheat the oven to 400° 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 375° 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 crème fraîche 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 crème fraîche. Sprinkle with remaining streusel.
Bake until crème fraîche 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.