Ingredients:

  • 2 1/2 cups All-Purpose Flour, plus extra for dusting
  • 1 cup (2 sticks) Unsalted Butter, very cold, cut into 1/2-inch cubes
  • 1 teaspoon Fine Sea Salt
  • 1 tablespoon Granulated Sugar (for dough)
  • 6–8 tablespoons Ice Water
  • 3 cups Fresh Blueberries
  • 2 cups Fresh Blackberries
  • 3/4 cup Granulated Sugar (for filling)
  • 1/4 cup Tapioca Starch (or cornstarch)
  • 1 tablespoon Fresh Lemon Juice
  • 1/2 teaspoon Pure Vanilla Extract
  • Pinch Ground Cinnamon or Nutmeg (optional)
  • 1 large Egg (for wash)
  • 1 teaspoon Milk or Water (for wash)
  • 1 tablespoon Demerara Sugar (for finishing)

Instructions:

  1. Combine Dry Ingredients: Whisk together flour, salt, and sugar in a large bowl or food processor.
  2. Cut in the Butter: Add the cold butter cubes. Pulse in the food processor (or cut with a pastry cutter) until the mixture resembles coarse breadcrumbs with some pea-sized chunks of butter remaining.
  3. Add Liquid: Gradually add ice water, one tablespoon at a time, mixing until the dough just comes together into a shaggy mass. Do not overwork.
  4. Divide and Chill: Divide the dough into two discs (one slightly larger for the bottom crust). Wrap tightly in plastic wrap and chill for at least 60 minutes.
  5. Preheat Oven and Prep Pan: Preheat oven to 425°F (220°C). Place a parchment-lined baking sheet on the lowest rack.
  6. Make the Filling: In a large bowl, gently combine the blueberries, blackberries, sugar, tapioca starch, lemon juice, vanilla, and spices. Mix just until the fruit is coated; set aside.
  7. Roll the Bottom Crust: Roll the larger dough disc into a 12-inch (30 cm) circle. Carefully transfer the dough to the pie plate. Trim the overhang to 1 inch.
  8. Add the Filling: Pour the fruit filling into the prepared crust.
  9. Roll and Top: Roll out the second dough disc. Either cut vents into a solid top crust or cut into 3/4-inch wide strips for a lattice top.
  10. Seal and Crimp: Lay the top crust or lattice over the filling. Trim and crimp the edges tightly to seal.
  11. Final Chill: Return the assembled pie to the freezer or fridge for 15 minutes. This is vital to help the pastry hold its shape.
  12. Glaze and Initial Bake: Brush the chilled crust with the egg wash (egg mixed with milk) and sprinkle generously with Demerara sugar.
  13. Start Hot: Place the pie on the preheated baking sheet. Bake at 425°F (220°C) for 15 minutes.
  14. Reduce Heat: Reduce the oven temperature to 375°F (190°C). Continue baking for 45–55 minutes, or until the crust is deeply golden brown and the filling is visibly bubbling thickly. Cover edges with foil if they brown too quickly.
  15. Cooling (Mandatory): Transfer the pie to a wire rack. Let the pie cool for at least 3–4 hours before slicing. If cut early, the filling will run out.