1/2 cup frozen broccoli, defrosted and roughly chopped
1/4 cup sour cream
1/2 teaspoon black pepper
1/2 teaspoon kosher salt
1 (17.3 ounce) box puff pastry, thawed
1 egg, beaten
1 tablespoon shredded Parmesan cheese
Preheat oven to 400 degrees F, and line a rimmed baking sheet with parchment paper.
In a medium mixing bowl, combine chicken, cheese, broccoli, sour cream, black pepper and salt. Set aside.
Unwrap one sheet of puff pastry on a floured work surface. Using a pizza cutter or knife, cut the pastry lengthwise into 3 equal strips, then cut each strip in half crosswise for a total of 6 equal-sized rectangles. Transfer the rectangles to prepared baking sheet and repeat with the other sheet of pastry.
Mound 3 tablespoons of the chicken mixture into the center of 6 puff pastry rectangles. Make sure to leave a 1/2-inch space along the edge of each rectangle. Brush the edges with beaten egg and top with the rest of the rectangles. Gently crimp the edges of each pocket with a fork.
Cut small diagonal slits at 1-inch intervals along top of the pockets. Brush top and sides of pockets with beaten egg and sprinkle with Parmesan cheese. Transfer the baking sheet to the freezer for 15 minutes before baking.
Bake pastries until puffed and light brown, about 15 to 20 minutes. Remove from oven and let cool slightly before serving.
To freeze the pockets, allow them to cool to room temperature, transfer to an airtight bag and return to the freezer. To reheat, microwave one pocket at a time for 3 minutes on high.