Core the apples and dice them into 1-inch cubes. Dice the onion into 1/2-inch cubes.
Over medium low heat, sauté the apples and onion in 1 tablespoon of the olive oil melted together with the unsalted butter. Cook for 10 minutes, until softened. Add the wine, cranberries, salt, and pepper, and let simmer for 5 minutes. Remove from heat and allow to cool; set aside.
Over medium high heat in a large pan, heat the remaining tablespoon olive oil and add the turkey sausage removed from the casings. Cook until browned well, breaking the pieces up with a wooden spatula or spoon, about 8 to 10 minutes.
In a large bowl combine the sautéed fruit/onion mixture, cooked sausage, chestnuts (whole or chopped), cornbread, and red pepper flakes (if using). Toss gently but well. Add the chicken broth and 3/4 cup of the Parmesan and toss again (may add another 1/2 cup broth if you feel the stuffing is too dry).
Oil a large casserole dish (8.5 x 8.5 inch) with olive oil or pan spray, then pour stuffing into dish. Be gentle when spreading it in the pan, you don't want to smash the bread cubes.
Sprinkle over the remaining Parmesan, and dot with the butter pieces.
Bake in 400 degree F oven on middle rack for 45 minutes to 1 hour, until the top is golden brown.