Preheat the oven to 425o F.
Line a baking sheet with parchment paper.
Split and seed the butternut squash.
Place squash on the parchment paper and drizzle with olive oil. Spread the olive oil evenly over the inside and season with salt and pepper.
Turn the squash face down and roast for 40-50 minutes until tender.
While roasting the squash, add ~1 Tbsp olive oil to the stock pot and heat to shimmering. Add the onion, carrot & celery with 1 tsp salt and gently brown. Add the garlic for the last minute and brown until fragrant (about 1 minute).
Let the squash cool, and then scoop out into the blender.
Add the onion, celery, carrot, garlic, nutmeg, and black pepper to the squash. Add 3 cups of broth, or up to the blenders fill line and process until smooth.
Add blender contents back to the stock pot to simmer, adding the 2 Tbsp of butter. Add a little more broth if you would like it a little thinner. Taste and adjust with salt and pepper.
Options: Add 1 tsp Maple Syrup or ¼ cup spiced rum to the simmering soup. Or, serve with a dollop of sour cream and a sprinkle of parsley or pepitas.