Prepare the Pie Crust:

• In a large bowl, mix 2 cups flour and 1 teaspoon salt. Cut in butter until the mixture resembles coarse crumbs.
• Sprinkle in water, 1 tablespoon at a time, mixing until the dough holds together. Divide dough into two parts, one slightly larger than the other. Wrap in plastic and refrigerate while making the filling.

Cook the Chicken:

• Heat olive oil in a large skillet over medium-high heat. Add chicken cubes and cook until browned. Remove chicken and set aside.

Make the Vegetable Mixture:

• In the same skillet, add the chopped onion and sauté until translucent. Stir in 1/3 cup flour, salt, and pepper, cooking for about 2 minutes.

Create the Sauce:

• Gradually pour in chicken broth and milk, stirring continuously. Bring to a simmer and let thicken. Add the potatoes and mixed vegetables. Return to a simmer and cook until the potatoes are tender, about 10 minutes. Stir in the cooked chicken.

Assemble the Pie:

• Preheat oven to 375°F (190°C).
• Roll out the larger piece of dough to fit a 9-inch pie dish. Pour the chicken and vegetable mixture into the crust. Roll out the second piece of dough and place over the filling. Seal the edges and cut away excess dough. Make several small slits in the top to allow steam to escape.

Bake:

• Bake in the preheated oven for 45 minutes, or until the crust is golden brown.

Serve:

• Let the pie stand for 10 minutes before serving.