Preheat oven to 350 degrees. Spray a 9x13 inch baking dish with a thin coat of olive oil or butter.
Brown sausage in a medium skillet. Remove sausage to drain.
2 cups sausage
Add the onion and celery to the skillet. Cook over medium heat, stirring as needed to avoid burning, until softened.
½ cup onion, ½ cup celery
In a large bowl, stir together sausage, vegetables, cornbread, French bread, and seasonings. Stir until evenly combined.
4 cups day-old cornbread, 4 cups day-old or toasted French bread, ½ teaspoon garlic powder, ¼ teaspoon ground sage, ¼ teaspoon ground thyme
Add up to 2 cups of chicken stock half cup at a time to moisten the bread and bring the ingredients together.
2 cups chicken stock
Transfer to casserole dish and distribute evenly.
Bake for 30 minutes until browned.
Notes
I recommend adding the broth in increments. Once all of the ingredients are combined, assess. Is the mixture still a bit dry? Go ahead and add the rest of the broth. If it's quite moist already, don't.
Just how dry your bread is determines how much moisture to add. It's a little bit variable and depends on if you prefer a more dry or moist stuffing.