2. On a rimmed baking sheet lined with parchment paper or a silicone mat, arrange the 12 thawed shells 2 inches part. Bake for 8-10 minutes or until shells are just risen.
3. Remove the shells from oven and peel away the perforated center. Add 1 piece of pancetta and press into the shell forming a cup. Carefully add the egg to the pancetta cup and top with 1/2 teaspoon Za'atar. Repeat with remaining shells.
4. Return to oven and bake for 10 minutes or until egg white is set. Serve immediately.