Preheat the oven to 400F. Spray a 9x13 baking dish with nonstick cooking spray and set aside.
In a large pot or Dutch oven, heat the butter over medium heat until melted.
2 Tablespoons butter
Add the onion and minced garlic. Sauté for about 5 minutes, stirring often until translucent.
1 large onion, diced, ½ Tablespoon minced garlic (about 3 cloves)
Add in the flour and stir for 1 minute to combine. Pour in the chicken broth and stir constantly, bringing to a boil and then cook for an additional 2 minutes or until thickened. Turn the burner (heat) off.
1/4 cup flour, 2 1/2 cups chicken broth
Add in the diced chicken, frozen veggies, fresh parsley, salt and black pepper. Stir well to combine.
4 cups (20 ounces) cooked and chopped chicken (see notes), 1 lb package (3 ½ cups) frozen mixed veggies, ¾ teaspoon salt, ½ teaspoon ground black pepper, ¼ cup chopped fresh parsley or 1 teaspoon dried
Pour the chicken mixture into the prepared 9x13 baking dish.
Cover the chicken and vegetable mixture with the puff pastry dough (see notes). Brush the dough lightly with milk (this will give the crust a crispy and shiny top!). Sprinkle the dough with flaked sea salt. Bake for 30 minutes or until the top is golden and bubbling. Remove from the oven and allow to rest for 10 minutes before serving.
1 puff pastry dough sheet, fresh or frozen, 1 Tablespoon milk, flaked sea salt
Store leftovers in an airtight container in the fridge for up to 3 days.
Video
Notes
Ingredient Tips - Three large chicken breasts are needed for 4 cups or 20 ounces of cooked diced chicken. To simplify, use store-bought rotisserie chicken or leftover roasted chicken.Prep Tips - Depending on the size of your pastry dough and preference, you can cut into thirds as you see in the photos or leave it whole. We use the Pepperidge Farm frozen puff pastry dough that is more square shaped and subsequently a little short for a 9x13 pan. Alternatively, you can divide the chicken and vegetable mixture between two 8x8 pans and top each pan with a whole sheet of puff pastry (there are 2 Pepperidge Farm frozen puff pastries in each package).Meal Prep Tips - The chicken and vegetable filling can be prepared and frozen in an airtight container for up to 3 months. Thaw filling and top with pastry dough when ready to bake.