Preheat your oven to 400°F and position the rack in the lower third. In a deep, oven-safe skillet, melt the butter over medium-high heat. Toss in the green onion whites and chopped carrots, stirring occasionally, until they soften—this should take about 6 minutes.

Sprinkle the flour over the veggies and stir constantly for a minute or two to cook out the raw flour taste. Slowly pour in the chicken broth, stirring as you go, and let the mixture come to a simmer. Keep stirring until it thickens, about 1 to 2 minutes.

Now, add in the shredded rotisserie chicken, peas, heavy cream, thyme, salt, and pepper. Give everything a good mix, then shut off the heat.

In a small bowl, whisk together the egg and a tablespoon of water. Roll out the thawed puff pastry into a 12-inch square, then cut it into smaller squares of desired size.

Lay the pastry squares over the chicken mixture in the skillet, slightly overlapping them to create a cozy, rustic top layer. Brush each square with the egg wash to get that golden, glossy finish. Place the skillet on a rimmed baking sheet to catch any spills.

Transfer the skillet (on the baking sheet) to the oven and bake for about 30 minutes, until the puff pastry is golden brown and crispy, and the filling is bubbling. Let it sit for 10 minutes before digging in. Enjoy!