Preheat oven to 400° F.
Thaw 16 ounces of frozen spinach.
Using a cheesecloth, squeeze as much water out as possible of both the spinach and 14-ounce can of chopped artichokes.
In a medium-sized bowl, combine spinach, artichokes, ½ cup chopped green onions, 8 ounces of feta cheese, 4 ounces of Parmigiano Reggiano cheese, 1 teaspoon salt, ½ teaspoon black pepper, 6 minced garlic, 4 tablespoons melted butter, and 2 beaten eggs.
Roll out 3 sheets of puff pastry separately to 10 x 10 inches. Using a pizza cutter, divide each sheet of the puff pastry into 9 equal squares giving a total of 27.
Spray your mini muffin tins with cooking spray. Press each puff pastry square into the bottom and sides of the muffin tins.
Place a heaping tablespoon of the spinach mixture into the square. Bring each corner up and twist to seal.
Brush the additional beaten egg onto each spinach cup.
Bake for 20-25 minutes until golden brown.
Serve either warm or at room temperature.
