In a large saucepan, bring one cup of the stock to a boil. Break the sausage into the pan and cook, stirring with a fork to break it up, until it no longer looks raw--about six minutes. Transfer the sausage to a bowl.
Heat the butter in the saucepan until it bubbles. Add the chopped onion, fennel, celery, and green onions. Sauté until tender. (Note: It might be easier to do this in two batches, starting with half the butter for each batch.) When finished, transfer the chopped vegetables to the bowl with the sausage.
Add a half-cup of stock to the pan and bring to a boil over medium heat. Add the spinach, parsley, salt, pepper, thyme, tarragon, and sage. Cook until the spinach and parsley wilt, then add the Herbsaint. Cook another minute, then turn off the heat.
Remove the spinach mixture and chop. Add the chopped spinach mixture to the sausage bowl. Toss all the contents of the bowl to mix well.
In another bowl, beat the eggs, then whisk in the half-and-half and the remaining chicken stock.
Break up the cornbread into morsels (not quite crumbs). Put the cornbread into a large bowl and add the milk-egg mixture. Stir lightly to combine.
Add the sausage mixture to the cornbread, and toss to combine. Taste and adjust seasonings with salt and pepper.
Load into a baking dish or two. Press down the top of the stuffing to flatten it out. Bake in a 400-degree oven for 30 to 40 minutes (longer for larger baking dishes), until the top has browned nicely.
