GRAVY/FILLING: In a large sauce pot, melt the butter over medium heat. Whisk in flour, cook for 2-3 minutes, whisking often. Slowly add milk and broth, continue whisking. Bring to a boil, once the sauce thickens up, add the chicken and veggies, cook for a few minutes more. Season with salt and pepper to taste. Pour the mixture into a 9x13-inch pan.
BISCUITS: Combine flours, baking powder, baking soda, and salt in large bowl. Cut butter into the flour mixture until mixture resembles coarse meal. Stir in buttermilk until combined.
Drop the biscuits on top of the filling, make them small, about 1 tablespoon size, I used a cookie scooper. Bake the pot pie for about 25-30 minutes, until the biscuits are golden brown. You can turn the broiler on, and brown them even more if you think it needs it. Serve and enjoy!
TO PREPARE THE BISCUITS ONLY, USE THE FOLLOWING INSTRUCTIONS: Adjust oven rack to upper-middle position and preheat oven to 425 degrees. Grease 9-inch cake pan.
Combine flours, baking powder, baking soda, and salt in large bowl. Cut butter into the flour mixture until mixture resembles coarse meal. Stir in buttermilk until combined.
Portion the biscuits using a greased 1/2-cup measuring cup or large spring-loaded ice cream scoop to transfer 6 heaping portions of dough into prepared pan, placing 5 around the pan's perimeter and 1 in the center.
Bake the biscuits until puffed and golden brown, 20 to 25 minutes. Cool in pan for 10 minutes, then transfer to wire rack. Serve. (Biscuits can be stored in airtight container at room temperature for 2 days.)
COOK'S NOTES: You could also use your own biscuit recipe, top with refrigerated biscuits or make Bisquick biscuits, if desired.