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.