Turkey Pot Pie with Cornbread Crust

Thanks neighbour Lori for putting me onto this recipe. It has become a family classic! The original recipe comes from Oprah's website and is originally made with chicken.
Enjoy!

Ingredients
Filling:
1 Tbsp. olive oil
1 Tbsp. unsalted butter
1 medium Onion , chopped
1/4 cup flour
2 cups chicken stock
2 cups chopped Roasted Chicken
1/2 cup frozen sweet petite peas
1 potato , diced and boiled
1 1/2 cup chopped, cooked carrots
1/2 tsp. salt
Cracked pepper
Dash of hot sauce
Crust:
3/4 cup white or yellow cornmeal
3/4 cup flour
1 Tbsp. baking powder
1 1/2 Tbsp. sugar
1/2 tsp. salt
3/4 cup milk
1 large egg
2 Tbsp. olive oil

Directions
To make filling: Preheat the oven to 400°. Spray a 2-quart casserole with cooking spray. In a large sauce pan, heat olive oil and unsalted butter together. Add onion and sauté until tender, about 4 or 5 minutes. Add in flour until blended. Slowly stir in 2 cups of heated chicken stock, whisking well. Cook mixture over medium heat until thickened and bubbly, about 4 minutes. Stir in chicken, peas, potato, carrots, salt, pepper and hot sauce. Pour into a 2-quart ovenproof casserole dish coated with cooking spray and spread mixture evenly.
To make crust: In a bowl, stir cornmeal, flour, baking powder, sugar and salt. Stir milk, egg and canola oil until well combined. Stir wet ingredients into dry ingredients. Spoon the batter evenly on the filling. Bake until the top is golden brown, about 22 to 25 minutes.