Thaw puff pastry according to package directions.
Preheat oven to 425 degrees F.
Meanwhile, in a large skillet melt butter over medium-high heat. Add chicken, sweet pepper, and shallots and cook 5 minutes, stirring frequently. Stir in flour, salt, tarragon, and black pepper. Add milk and cream all at once. Cook and stir until thickened and bubbly. Stir in wine, peas, carrots and potatoes; heat thoroughly. Transfer the hot chicken mixture to a 1 1/2-quart casserole. Place pastry over the hot chicken mixture in casserole dish. Brush puff pastry with egg wash then cut slits in the pastry to allow steam to escape. Bake in the preheated oven for 30 to 45 minutes.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.