01 - Preheat oven to 400°F.
02 - Heat olive oil in a large skillet over medium heat. Add onion and garlic; sauté until soft and translucent, about 4 minutes.
03 - Add shredded chicken to the skillet and stir until heated through. Remove from heat.
04 - In a large bowl, combine ricotta, heavy cream, parsley, thyme, rosemary, salt, pepper, and lemon zest. Mix well until smooth and incorporated.
05 - Add the chicken mixture to the ricotta mixture and stir until evenly combined.
06 - Line a 9-inch pie dish with one sheet of puff pastry, pressing gently to fit the contours and trimming any excess overhang.
07 - Spoon the filling evenly into the pastry-lined dish, spreading smooth.
08 - Cover with the second sheet of puff pastry. Trim edges, pinch firmly to seal, and cut a few small slits in the top to allow steam to escape during baking.
09 - Brush the top pastry with beaten egg for a golden, glossy finish.
10 - Bake for 40 to 45 minutes, or until the pastry is deeply golden brown and crisp.
11 - Let the pie cool for 10 minutes before slicing and serving to allow the filling to set.