Prepare the cornbread as directed. If you can, make this several days ahead so it has time to dry out. If that's not possible, just break it up, and then put it in the oven to toast on 300 degrees for about 30 minutes. It doesn't need to be crunchy dry, just not moist and fresh.
In a large frying pan, add butter, chopped onion, bell pepper and celery. Sauté over medium-high heat, stirring occasionally, for 15-20 minutes, until veggies are very tender. Season with sea salt, black pepper, poultry seasoning, and add chopped sage and rosemary.
Use to stuff a turkey or a chicken, or add to a baking dish to cook separately. If cooking the stuffing separately, moisten stuffing with 1/2 cup-3/4 cup of drippings from the cooked turkey or chicken, or use chicken or vegetable stock.
When baking stuffing separately, I like to bake it uncovered so the top gets crunchy. I generally just put it in the oven with whatever else is baking- roasted veggies or a chicken.
If baking on it's own, bake at 400 degrees Farhenheit for 20-25 minutes, until hot throughout and lightly toasted on top.