Melt 2 tablespoons of unsalted butter in a large skillet over medium heat. Add finely chopped shallots, diced carrots, and sliced celery, sauté until softened, about 4-5 minutes.

Sprinkle 1/4 cup flour over the vegetables, whisking for about 1 minute. Gradually add 3/4 cup white wine while whisking continuously until the mixture thickens into a roux.

Whisk in 2 cups chicken stock and 1/2 cup heavy cream, bringing to a gentle simmer. Cook for about 10 minutes until the sauce is smooth.

Add the shredded rotisserie chicken, 1 cup frozen peas, and 1/4 cup chopped parsley into the mixture, stirring until combined and heated through.

Roll out thawed puff pastry on a lightly floured surface and cut to cover the pie dish. Brush edges with butter or egg wash.

Pour the creamy filling into the pie dish, lay the puff pastry over the top, sealing edges, and brush with egg wash. Bake at 400°F (200°C) for 20-25 minutes until golden brown.