Preheat oven to 375 degrees. Spray an 8 inch square baking dish with gluten-free non-stick cooking spray.
Whisk all ingredients in a large mixing bowl just until combined. A few lumps are ok. Pour into prepared baking dish and bake for 30-35 minutes or until golden brown and a toothpick inserted in the center comes out clean.
Let cornbread cool and then crumble onto a baking dish and let dry out overnight.
Place cornbread crumbles in a large mixing bowl. Cook the sausage over medium heat until fully cooked. Pour off the fat and add ½ cup of butter or Earth Balance. Add the chopped celery, onions and leeks. Cook until the vegetables are translucent but not too browned, about 10 minutes. Add the sausage/vegetable mixture into the bowl with the cornbread crumbles along with the melted butter and add the eggs, poultry seasoning, salt and pepper. Mix well. Add just enough chicken stock to make the mixture moist but not mushy.
Stuff the cavity of the turkey with some of the stuffing being careful not to overfill. Place the rest of the stuffing into a butter casserole dish. Pour about ¼ cup more stock over the top of the stuffing and dot the top with the remaining butter that has been cut into small pieces. Bake for 30 minutes in a 350 degree oven.
This gluten free recipe makes enough to stuff a 20-pound turkey with an extra casserole.