Preheat oven to 400°F. Dress butternut squash with olive oil, salt, pepper and a little nutmeg. Roast to golden brown and cooked through, 20-25 minutes.
Heat oil, 1 turn of the pan, in a large, deep skillet over medium-high heat. Brown and crumble sausage; remove. Add butter, melt then add apples, celery and onions. Season with salt, pepper and herbs; cook to tender, 8-10 minutes.
In a small skillet, combine stock, jam, mustard and syrup. Simmer to thicken into a glaze/sauce, 5 minutes or so.
Combine squash, sausage, apples, celery and onion, and stir in the glaze to coat and make your stuffing ingredients cling to each other.