Preheat the oven to 400.
In a small pot add the apple cider, gizzards, and a pinch each of salt and black pepper. Bring to a simmer and allow the cider to reduce until the gizzards are cooked through (about 15 minutes). Set aside.
Sear the sausage on both sides in a large pan until mostly cooked through (but not all the way). Remove from a pan and place in a large bowl. Set aside.
In the same pan, cook the diced celery, onion and peppers (add a little olive oil if needed). Season with salt and pepper.
Once the vegetables have softened, remove from the heat, add the herbs and toss together. Add the cinnamon and nutmeg and toss together again.
Break the cornbread up into cubes. In a large bowl, toss the vegetables with the cornbread - don't worry about breaking the cornbread up too much, just get it all mixed in evenly.
Cut out the sinew part of the gizzards and discard. Dice the rest of the gizzards finely and add to the cornbread. Slice the Italian sausage into 1/4-1/2 pieces and add that (and any juices from the sausage) to the cornbread as well. Toss together.
Add the breadcrumbs and reduced apple cider and toss together. Add as much unsalted chicken stock as is needed to moisten the cornbread crumbs, but don't add so much that liquid begins to pool in the bottom of the bowl. Season again with a few pinches of salt and black pepper, and toss together.
Pour the mixture into the same pan used for the cornbread. Bake, uncovered, in the 400 degree oven for 10 minutes. Drop the temperature down to 350 and bake for another 40-50 minutes until the top is evenly browned with a few darker edges.
Remove from the oven and cover with tin foil until ready to serve. Can wait at room temperature up to 1 hour.