Preheat your oven to 425°F (220°C).

In a large pot over medium heat, melt the butter. Add the flour and stir until smooth, then gradually add the chicken broth and milk while stirring constantly. Bring this mixture to a boil and allow it to thicken.

Once thickened, mix in the chicken, frozen veggies, salt, pepper, onion powder, and garlic powder.

In a bowl, combine the flour and salt for the crust. Add the diced cold butter and mix until it resembles coarse crumbs. Gradually add ice water until the dough comes together.

Roll out the crust and place half in a pie dish. Pour the filling over the crust and cover with the remaining crust. Seal the edges and cut slits on top.

Bake the pie in your preheated oven for 30-35 minutes or until the crust is golden brown and the filling is bubbling.

Let it cool for a few minutes before serving.