These are individual servings. If I'm going to bake anything, I want it at its best, and that means fresh from the oven, warm, and the 'individual pie servings' approach fit very well.
Any crust recipe you prefer, or store bought, if you want to make one larger pie.
5 cups frozen berries (use any you like, and adjust sugar according to the berry sweetness)
1/2 cup sugar (I like a bit of tartness in my berry pies)
1/3 cup flour
In a small bowl, set your berries out to thaw. Once thawed, add the sugar and flour, and stir to combine, mashing up the berries a little as you go.
Roll out your pie dough, and using any small plate, or bowl, shape 6" circles (or as close as you can get). My bowl had a good edge for cutting through the crust, but if you don't have that, just use a knife to cut around the edge of the bowl or plate you choose as your form.
You should end up with about a dozen circles of dough.
Divide up the filling among your dough circles, and place the filling in the middle of each circle, and top with a thin butter slice, about 1/8" thick.
Lightly moisten edges of dough with water, fold over, and press lightly with your fingers. Finish sealing with a press from a fork, all the way around the sealed edge. To keep dough from sticking to your fork, dip in flour following each depression.
Pre-heat oven to 425 degrees.
Place pies on a parchment lined baking sheet, and apply an egg wash. Place in the oven, and immediately reduce heat to 375 degrees. Pies are done when they are golden brown.
Allow to cool for 15-20 minutes, then plate and garnish as you wish. Powdered sugar is pretty, and adds just a touch of sweetness to the crust. Vanilla ice cream is a nice add, as well, or a sprig of mint.