Ingredients:
For the pie & filling:
1 batch of your favorite pie dough, prepared and well-chilled
6 cups(1010 grams) berries, trimmed and halved (or quartered, if large)
1 tablespoon(15 grams) freshly squeezed lemon juice
1/3 cup(66 grams) granulated sugar
1/3 cup(71 grams) light brown sugar
1/3 cup(40 grams) all-purpose flour
3/4 teaspoonground cinnamon
1/2 teaspoonfine sea salt
1 vanilla bean, halved and scraped, 1 teaspoon vanilla bean paste, or 2 teaspoons vanilla extract
For the drop biscuit topping & assembling the pie:
1 cup(120 grams) all-purpose flour
1/4 cup(53 grams) light brown sugar, packed
3/4 teaspoonbaking powder
1/4 teaspoonbaking soda
1/2 teaspoonfine sea salt
4 tablespoons(57 grams) cold unsalted butter, cut into ½-inch / 1-cm cubes
1/2 cup(120 grams) buttermilk
1/2 teaspoonvanilla extract
Turbinado or coarse sugar, for sprinkling
Directions:
Make room in your refrigerator for your deep-dish pie pan.
On a lightly floured surface, roll out the dough into a round ¼-inch thick. Use scissors to trim away any excess dough to leave just a ½ inch/1 cm border of excess dough around the outer edge. Use your fingers to tuck this dough under itself all the way around, then crimp as desired. Use a fork to poke holes all over the base and sides of the dough, then refrigerate for 30 minutes.
Towards the end of chill time, heat the oven to 400°F/200°C with an oven rack in the center. Line the pie with parchment paper or foil, and fill to the top edge with pie weights (I use ceramic pie weights, but dried beans or legumes also work great). Place the pie pan on a parchment lined baking sheet. Transfer to the oven and bake until the edge is lightly golden brown, 15 to 18 minutes. Remove the pie weights, prick the dough a few more times with a fork, and return to the oven until the base and sides appear dry and matte, 3 to 5 minutes more. Cool completely before using.
In a large bowl, toss the berries with the lemon juice and granulated sugar. Let macerate for at least 1 hour, or up to 3 hours; toss the berries occasionally during the first 15 to 20 minutes to help ensure they’re all getting evenly juicy.
Place a colander over a medium pot and pour the berries into it. Press down gently on the berries—you don’t want to smoosh the fruit too much, but you want to get all of the juices that you can into the pot. Transfer the berries to a bowl. Set the pot over medium heat, bring the juices to a simmer, and simmer until they have reduced to 80 grams (¼ cup). (The amount of time this takes will depend on how much juice your berries yield—more juices from super ripe summer fruit will take longer, while out of season fruit might only take a few minutes.) Remove from the heat.
In a small bowl, mix the brown sugar, flour, cinnamon, salt, and vanilla bean seeds, if using (if using extract, you will add it later). Use your fingers to mix the ingredients until they’re uniformly combined. Toss the brown sugar mixture with the berries to combine well, then pour the reduced juices over and toss again. (If using vanilla extract, add it and toss to combine.) Transfer this mixture to the cooled crust in an even layer.
Heat the oven to 375°F/190°C with a rack in the lower third of the oven.
Make the biscuit topping: In a medium bowl, whisk the flour, brown sugar, baking powder, and salt to combine. Add the butter and mix with your hands or a pastry cutter until the butter is almost fully incorporated into the flour, with just a few small visible pieces remaining.
Add the buttermilk and vanilla extract and mix until a sticky batter forms. Dollop the biscuit topping randomly over the surface of the pie. You may not cover the whole surface of the pie; that’s ok (and remember the biscuit will also spread). Sprinkle the surface of the biscuit generously with turbinado sugar.
Transfer the pie to the oven and bake until the crust is deeply golden brown and the filling is bubbling around the edges and/or a tester inserted into the center of the biscuit topping comes out clean, 60 to 75 minutes. Cool completely before slicing and serving.