Prepare dough into two circles and chill for at least an hour or overnight. Roll one circle of dough about 1/4 inch thick and line a deep dish pie pan leaving about a 1 inch overhang. Place lined pie pan in the refrigerator.
Line a baking sheet with parchment or wax paper. Roll the other circle of dough into a 1/4 inch thick circle. Using a pizza cutter or sharp knife, cut circle into 12 strips about one inch wide.
Gently place strips on baking sheet, cover lightly with plastic wrap and place in refrigerator.
Grate apples, squeeze out moisture and set aside.
In a large bowl, mix blueberries and blackberries with grated apple. Gently toss mixture with lemon juice.
In a large bowl, mix blueberries and blackberries with grated apple. Gently toss mixture with lemon juice.
In a small bowl, mix together sugar, cornstarch, lemon zest, salt and cinnamon.
Add sugar mixture to berries and gently stir to evenly distribute. Add vanilla. Transfer mixture to prepared pie plate and dot the top with butter.
Make the lattice crust
Lay five strips vertically across the pie, spaced evenly.
Fold back strips 1,3,5 halfway down and lay one strip across the center of the pie horizontally.
Unfold the strip and fold down strips 2 and 4. Place another horizontal strip across the pie and continue this pattern until you have covered the entire pie.
Tuck the strips under the overhang from the bottom crust. This is the part I’m not great at, but don’t sweat this – you want your pie to look rustic. Once everything is tucked under as best you can, crimp the edges or you can press the edges down with fork tines.
Combine egg with 1 Tablespoon of water in small bowl. Brush lattice crust lightly with egg wash and sprinkle with sugar.
Place in lower third of oven and bake at 425 for 30 minutes. Reduce heat to 375 and bake for another 20-30 minutes until juices and thick and bubbly. Let pie cool for AT LEAST two hours – the more the better. This is a juicy pie and needs the time to cool down and set.
Enjoy the best pie you’ve ever made!