Preheat oven to 425 degrees
Line a 9"x13" baking pan with parchment paper
In a bowl, mix 3 cups berries with sugar, cornstarch, juice and zest of one lemon, let that sit for the juices to come out about 15 minutes.
Roll out your 2 pie crust to an approximate 9" x 12" rectangle, make one slightly bigger. If it gets too soft chill in refrigerator.
Lay your slightly larger slab of your rolled out pie crust over the parchment lined pan, add your berry mixtures with a slotted spoon, we don't want soggy pie.
Lay your other pie crust over the the berries, pinch the edges all around. Cut a few slits over the top to vent.
Mix egg with a tablespoon of water, brush all over the pie.
Bake for 30-35 minutes until bubbly and golden. Allow to cool completely before slicing.
If making cream cheese drizzle, mix cream cheese, powdered sugar and milk until drizzling consistency. If too soft, add a bit more powdered sugar, if too stiff, add more milk. Add to a sandwich zipper bag, snip off end and drizzle. Add berries to garnish on top.