1. Heat oven to 400ºF. Remove pie crusts from packages and set out to bring to room temperature.
2. Crumble the feta cheese into a medium bowl and mash with a fork. Over a large bowl, squeeze the liquid from small handfuls of the thawed spinach. As each handful is squeezed dry, toss it into the bowl with the cheese. Pour out the spinach liquid.
3. Add egg, parsley, salt, and pepper and stir until well mixed.
4. Carefully unfold a pie crust onto a lightly floured surface. Press out any fold lines with your fingers. Using a 2 1/2- to 3- inch round cookie cutter (or the rim of a juice glass), cut the pastry into circles. (Start at the outer edge of the crust and work toward the center to maximize the number of rounds.) Repeat with the other crusts, discarding scraps.
5. To form a pocket, place 1 1/2 teaspoons of filling on one half of a pastry round. Fold the other half over to make a half circle. Press the tines of a fork along the curved edge to crimp and seal the pocket. Repeat to fill and fold all pockets.
6. Place pockets on a nonstick baking sheet and prick tops with a fork to vent. Bake for 10 minutes, or until lightly browned. Serve warm or at room temperature.
How Kids Can Help: All steps except those that involve heat.