Blueberry Streusel Pie

Ingredients:

Cake

• 3/4 cup whole wheat flour
• 3/4 cup wheat flour, plus more for dusting
• 1 tbsp. granulated sugar
• 2 tsp. table vinegar (5%)
• 1/2 tsp salt
• 10 tbsp (140 g) cold unsalted butter, cut into small pieces

Filling

• 6 cups blueberries
• 3/4 cup granulated sugar
• 2 wide strips of lemon zest
• 1 tbsp fresh lemon juice
• 3 tbsp. whole grain flour
• 1/4 teaspoon freshly grated nutmeg
• 1/8 tsp salt

Streusel

• 3/4 cup coarsely chopped toasted almonds, walnuts, or hazelnuts
• 1/2 cup light brown sugar
• 1/2 cup whole wheat flour
• 4 tbsp (60 g) unsalted butter, melted
• A pinch of salt

Preparation:

1. Prepare the dough: Combine both flours, granulated sugar, vinegar, salt, and about one-third of the butter in a food processor. Turn on and pulse until the butter is incorporated. Add the remaining butter and pulse until pea-sized pieces form. Add 2 tablespoons of ice water and continue to pulse until the dough begins to come together. Pinch off a small piece of dough; if it doesn't stick together, add another 2 tablespoons of water and pulse. Wrap the dough in plastic wrap and form it into a ball. Then shape it into a 12 mm thick disk. Chill the dough for at least 1 hour, until firm.
2. Roll out the dough into a 12-inch circle on a lightly floured work surface or between 2 sheets of lightly floured parchment paper. (If the dough becomes soft, chill until firm.) Place the dough in a 9-inch round baking pan. Smooth it out evenly and tuck in any excess edges; chill for 30 minutes. Meanwhile, preheat the oven to 350°F (180°C).
3. Using a fork, prick the bottom and sides of the cake, then line it with parchment paper and fill with dried beans. Bake for 20 minutes, then remove the parchment and weights and continue baking until light golden brown, about 10 more minutes. Remove the cake from the oven and cool completely.
4. Meanwhile, prepare the filling: Combine 3 cups blueberries, 1/2 cup granulated sugar, and lemon zest in a saucepan. Place the saucepan on the stove and simmer over low heat, breaking up the berries with a wooden spoon, until the liquid is reduced by half, about 20 minutes. Discard the lemon zest. Pour the blueberry mixture into a bowl; stir in the remaining 3 cups berries and 1/4 cup granulated sugar, lemon juice, flour, nutmeg, and salt. Cool completely.
5. Prepare streusel: Mix nuts, brown sugar, flour, butter, and salt. Using your hands, form the mixture into small balls and pour onto a baking sheet. Freeze for 30 minutes.
6. Increase the oven temperature to 190°C. Fill the crust with blueberry filling and sprinkle streuselPlace the pie in the oven and bake for 45 to 55 minutes, until golden brown. (If the topping begins to burn, cover the pie with foil.) Remove the pie from the oven and let it cool overnight, or for at least 4 hours, so the filling will set.