Preheat oven to 400 degrees.
Melt the butter in a large pot over medium heat.
Whisk in the flour and cook for 30 - 60 seconds.
Add the milk and the chicken broth.
Whisk in the cheese sauce mix from box of potatoes.
Stir in the julienne potatoes.
Cook over medium heat for 6-8 minutes, stirring often, until thickened.
Stir in the ham and the frozen veggies.
Spread the mixture in a greased 9×13 pan.
Cover with pie crust.
Poke holes in the crust and bake at 400 degrees for 40-45 minutes, until golden.
(If you want a more golden crust, you can brush it with an egg wash.)