1. Preheat oven to 400°F (200°C) and line a baking sheet.

2. Slice acorn squash in half lengthwise, remove seeds, brush with olive oil, salt, and pepper, place cut-side down on baking sheet and roast for 25–30 minutes until tender.

3. While squash roasts, heat oil in a skillet over medium heat, crumble chicken sausage, and cook until browned, about 5–6 minutes.

4. Add onion, celery, and garlic to skillet and cook until softened, then stir in apple, spinach, herbs, and cooked grains if using; season with salt and pepper.

5. Remove squash from oven, turn cut-side up, fill cavities with sausage mixture, top with cheese and bread crumbs if desired.

6. Bake stuffed squash for an additional 10–15 minutes until topping is golden and filling is heated through, then cool slightly before serving.