chicken and stove top stuffing style casserole

1 rotisserie chicken
Skinned deboned and chopped
Or
2-3 lb cooked diced chicken
2 cans cream of chicken soup
One can of peas
One can of carrots
Three cups of water
One cup of milk
3 tbsp of butter
Two and a half cups instant mashed potatoes
You may double this if you want a thicker layer of mashed potatoes
Two boxes of stove top stuffing chicken flavored
One stick of butter
Three cups of water
If you want a thicker layer of stuffing
You can add another box
In this case you would want
1 and 1/2 sticks of butter
Four and a half cups of water
And three boxes of stuffing
Three 9 inch baking dishes
Or one deep 9x13
Oil for greasing baking dishes
Or cooking spray