Prepare either pie crust recipe through step 5, including chilling for at least 2 hours. I usually make the crust the night before. The pie crust recipe makes 2 crusts and you’ll be using both crusts.

Place 1/2 cup of each type of berry in a medium bowl and set aside.

Place the remaining 2 and 1/2 cups blueberries, 1 cup raspberries, and 1 cup blackberries in a medium saucepan set over medium heat. Add the sugar and cinnamon, and cook, stirring frequently, until the berries begin to release some juice.

Place the cornstarch and lemon juice in a small bowl. Remove 3 to 4 Tablespoons of warm berry juice from the saucepan and add it to the bowl of cornstarch. With a fork, whisk together until smooth.

Stir the cornstarch mixture into the saucepan with the berries. Cook, stirring occasionally, until thickened into a jam consistency, about 5-7 minutes. If you have an instant-read thermometer, the filling is done when it reaches about 185°F (85°C). Stir in the reserved berries, lemon zest, and vanilla. Cool for 20 minutes at room temperature.

Adjust the oven rack to the lower third position and preheat to 425°F (218°C). Place a baking sheet on the bottom oven rack.

Roll out one of the discs of chilled dough on a floured surface into a 12-inch circle. Place it in a 9-inch pie dish.

Spoon the filling into the crust and chill as you prepare the top crust.

Roll out the second disc of dough and cut strips for a lattice top. Weave the strips over the filling, trim excess, and crimp the edges.

Brush with egg wash and sprinkle coarse sugar on top.

Bake at 425°F for 20 minutes, then reduce temperature to 375°F (190°C) and bake for 45-55 minutes or until bubbling.

Cool on a rack for 5 hours before serving.