Preheat your oven to 375 degrees and put a large sheet pan lined with foil into your oven while it preheats.

Roll out your bottom crust and fit it into an 8 inch pie tin, leaving about a 1 inch overhang. Place the whole tin into the fridge while you make the filling and top crust.

Hull and chop your strawberries into small chunks, about the same size as your raspberries. If your blackberries are large, slice them in half.

In a medium bowl, stir together all the berries, cornstarch, lemon juice, sugar, and salt until well combined. The mixture should look like a thick paste surrounding the berries.

Roll your second crust out. If desired, you can do a lattice method, or to replicate my pie, slice the dough into thin strips and braid into three large braids. Remove the bottom crust from the freezer and add the berry filling. Roughly chop the pistachios, and sprinkle about half of the pistachios on top of the filling.

Then top your pie with the second crust carefully. Brush the top with your beaten egg, and sprinkle on the remaining pistachios along with the coarse sugar.

Carefully place the pie in your preheated oven on top of the hot baking sheet. Bake for 40-45 minutes, or until the crust on top is golden brown all over and the filling is bubbly. Serve warm with whipped cream!