Preheat the oven to 400°F. Place the squash on a rimmed baking sheet, drizzle over the melted butter, season with salt and pepper and toss to combine. Spread out in a single layer on the baking sheet, allowing space in between the cubes when possible. Roast for about 25 minutes until tender and lightly browned on the bottom.

Heat the oil in a stockpot over medium heat Add the shallots and sauté for 10 minutes, until the shallots have softened and turned a light golden brown. Add the broth and bring to a simmer.

Add the cooked butternut squash to the simmering broth and working in batches, puree the soup in a blender or food processor (alternately you can run the mixture through a food mill, which offers a great kind of nubby texture, or puree right in the pot with an immersion blender). Return the pureed soup to the pot. Taste and adjust the seasoning.