Preheat the oven to 450°F.

In a medium saucepan, melt butter over medium heat. Add diced onions and saute until onion is translucent (3-4 minutes).

Add flour, salt, and pepper. Cook, stirring constantly, until flour mixture begins to brown (3-4 minutes).

Slowly stir or whisk chicken broth and whole milk into the flour mixture. Stir constantly while pouring just a bit at a time to make a smooth mixture.

Continue cooking over medium heat, stirring constantly to ensure milk does not burn on the bottom of the pan, Cook until mixture begins to bubble and thicken slightly (about 5 minutes). Remove from heat.

Stir in cream cheese, frozen vegetables, and diced chicken. Stir to mix evenly. Set aside.

Prepare pie crusts, fitting the bottom crust into a 9” pie plate with edges hanging over for crimping in the next step.

Spoon chicken pot pie filling into the pie crust, spreading evenly. Place top crust over the filling.

Fold under the overhanging edges so that the top and bottom crusts come together and seal at the edges. Crimp.

Brush the top of the pie with egg yolk mixture and slit the top in a few places for venting.

Bake for 15 minutes in the 450°F oven. Check pie for a deep golden brown. When it is browned to your preference, cover with aluminum foil and continue baking 15 minutes longer until bottom crust is also cooked and filling is bubbling up under the crust.

Cool for at least 15 minutes before cutting and serving.