For easy chicken pot pie casserole, gather 1 1/2 pounds chicken, 1 cup each carrots, peas and frozen pearl onions, 2 cloves garlic, 2 cups chicken stock and 1 cup heavy cream. Also obtain a store-bought pie crust, 1 egg, 1/4 teaspoon oregano, 1/2 teaspoon sweet paprika and sage.
Season chicken with herbs, paprika, salt and pepper, and cook it in a heavy, oven-safe skillet that you've brought to medium-high heat with 3 tablespoons olive oil. Cook for about four minutes on the first side, then flip the pieces over, and continue cooking them for an additional three. Remove chicken to a separate plate, allowing it to rest before chopping it into roughly equal-sized cubes. Season and cook vegetables in remaining oil for about five minutes, then add garlic and sauté until fragrant.
Sprinkle the contents of the skillet with flour, then add the chicken stock. Bring to a simmer, and allow the flour to start thickening the liquid into a gravy. Next, add the heavy cream, and stir it in. Place the cut chicken back in the pan, mix all contents, and layer the store-bought pie crust on top, making sure to tuck the edges inside the pan without actually touching the pan. Brush the top with the beaten egg, and cut three slits in the crust to act as vents. Place the entire skillet in an oven preheated to 400 degrees Fahrenheit for approximately 20 minutes. The finished crust should be golden brown.