Roll out your two pie crusts into circles with approximately 9-10” diameter. Place one pie crust in your 9” pie plate (standard size, not deep dish). Chill both the pie plate and the rolled out pie crust for at least 30 minutes.
Remove the rolled out pie crust from the refrigerator. Slice it into strips, about 1/2-3/4” per strip. Chill for 10 more minutes.
Make your filling: mix the berries, sugar, lemon juice, cinnamon, and cornstarch in a medium bowl. Make sure your berries are thawed and drained before using them so your pie isn’t too liquidy.
Place the berries in the chilled pie plate.
Remove the sliced crust from the refrigerator. Starting at one edge of the pie, use every other strip from the cut slices and place them equally distant from each other on your pie (space them about the same distance as the width of each strip).
Starting at one end of the pie, fold back every other strip and place the shortest remaining strip perpendicular to the strips already on the pie. Lay the folded strips flat.
Now, working at the opposite end of the pie, fold back the strips you didn’t fold back the first time. Take the next smallest strip of crust and place it parallel to the strip you just put down. Re-lay the folded strips flat.
Continue this process until all the crust has been used. Crimp the edges of the pie as desired.
Chill while the oven preheats to 425°F.
Brush the crust with eggwash and sprinkle sugar on top. Bake on an cookie sheet (in case of spillover) for 10 minutes at 425°F then reduce the oven temperature to 350°F for an additional 35-45 minutes until the crust starts to turn golden brown. It won’t get fully golden but some parts will start to turn.
Cool completely before slicing. To help the pie not run, it’s best to chill the cooled pie for a few hours before cutting.
Serve with ice cream and/or whipped cream, for garnish.