Preheat oven to 400°F first.
Peel and cube butternut squash carefully.
Toss squash with olive oil thoroughly.
Roast squash for 25 minutes exactly.
Heat butter in large pot gently.
Sauté onion until soft and translucent.
Add minced garlic for one minute.
Pour vegetable broth into the pot.
Add roasted squash to broth mixture.
Simmer everything for 15 minutes total.
Blend soup until completely smooth texture.
Stir in heavy cream very slowly.
Season with salt, pepper, and nutmeg.
Taste and adjust seasoning as needed.