In a deep pot, melt butter and whisk in flour slowly to combine.
Cook 1 minute.
Add chicken broth and heavy cream.
Stir to combine and simmer on low to thicken a bit.
Add carrots, peas, corn and chicken.
Season with salt/pepper and combine well.
Pour into a large casserole dish (9x13) so the potatoes do not overflow!
Potatoes
Boil potatoes and simmer until tender.
Drain and return to the pot.
Heat butter and milk.
Add slowly to the potatoes and beat on low with a hand held mixer.
Add sour cream and kosher salt/pepper.
(If too thick, you can slowly add up to 1/2c. more milk)
Scoop potatoes on top of pot pie filling.
Grate cheese on top!
Bake at 400 for 35-40 minutes until golden brown.