Preheat oven to 400° and generously rub a 10-inch skillet with butter all over the bottom and up the sides.
Combine all the dry ingredients in one bowl and whisk together.
In another bowl, combine all the wet ingredients and whisk until smooth.
Slowly pour in wet ingredients into dry ingredients while whisking and whisk until evenly incorporated.
Spread cornbread batter evenly in the skillet and bake for 20-22 minutes. (Until the toothpick inserted in the center comes out clean.)
Let cornbread cool for about 10 minutes in the skillet and then turn it over onto the cutting board.
Prepare the vegetables while cornbread is baking.
Set oven to 375° and rub a 9×13 baking dish with butter all over the bottom and up the sides.
Dice onions and celery and mince garlic.
Preheat a cooking pan over medium heat and add butter. Saute onions and celery until soft. Add minced garlic and saute for a few more minutes. Take off heat.
Crumble cooked cornbread in a large mixing bowl. (I like to leave some pieces larger and some smaller for the best dressing texture.) Add sauteed vegetables, salt, garlic powder, pepper, sage, and parsley.
Whisk eggs, warmed stock, and melted butter in another bowl and pour it all over the cornbread mixture. Mix everything together well.
Spread the mixture evenly in the prepared baking dish and bake for 25-30 minutes, until the top is golden brown and the middle is set.