Heat a large skillet over medium-high heat and stir in the ground beef and ground lamb, chopped onion, pine nuts, cinnamon, and salt and black pepper. Cook and stir until the meat is crumbly, evenly browned, and no longer pink. Drain and discard any excess grease.
Stir in the lemon juice; taste and adjust the seasonings, and let the meat mixture cool.
Preheat an oven to 350 degrees F (175 degrees C). Lightly grease a baking sheet or line it with parchment paper.
Roll out the thawed pastry sheets to about 1/8-inch thickness. Using a sharp 3-inch round cookie cutter, cut out at least 9 rounds per sheet. Lightly brush the inside edges with a little water, and place about 2 teaspoons of filling into the middle of each round. Fold the pastry round in half to cover the filling and seal the edges well. Transfer to the prepared baking sheet and repeat with the remaining dough circles.
Brush each pie with a little egg wash. Bake in the preheated oven until golden brown, 15 to 20 minutes.
