Heat the oven to 350 degrees, and line a large baking sheet with parchment paper.
In a bowl, mix together the cream cheese, milk, turkey, onion, butter, salt and pepper until well combined.
Lay the sheets of puff pastry onto a piece of parchment paper or a lightly floured surface, and use a rolling pin to roll them into roughly 11x11 inch squares.
Cut each sheet of puff pastry into 4 equal sized squares.
Place an even amount of filling into the center of each square of puff pastry.
Brush the edges of each puff pastry square with some water, and fold on corner of each square over to the other to form triangles.
Crimp the edges of each turkey pocket closed with the tines of a fork.
Place the turkey pockets onto the baking sheet, and bake for 25-30 minutes until golden brown and cooked through.