Preheat the oven to 425 degrees. Place the diced squash on a parchment lined baking sheet. Toss evenly with 2 tablespoons of oil and the salt.
Roast in preheated oven for 30-40 minutes until lightly browned and cooked through. While roasting get other ingredients ready.
Heat a large cast iron or oven-safe skillet to medium/high heat and 2 tablespoons oil. Add the onion, celery and a pinch of salt and cook for 3-5 minutes. Add the ground sausage to the skillet and use a wooden spoon to break up the meat while it cooks, about 3-5 minutes.
Add the chopped apples and cook until just soft, about 3-4 minutes. Add the rosemary, parsley and pepper and let cook for 2 minutes.
Once the squash is done roasting add it to the cast iron along with the cranberries. Stir to combine. (If you can't fit everything in the skillet, transfer to a larger baking dish).
Lower oven heat to 375 degrees and bake for 15-20 minutes until crispy on top.