Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).
Toss the cubed butternut squash with 1 tablespoon of olive oil, salt, and pepper on a large rimmed baking sheet.
Slice the top off the garlic head to expose the cloves, drizzle with the remaining tablespoon of olive oil, wrap tightly in aluminum foil, and place on the baking sheet.
Roast for 40 to 45 minutes until the squash is fork-tender and the garlic is soft and caramelized.
Allow to cool slightly, then squeeze the roasted garlic cloves out of their skins directly into a high-speed blender.
Add the roasted squash, dried sage, nutmeg, vegetable broth, and heavy cream to the blender.
Puree on high until the sauce is completely smooth and velvety.
Transfer to a saucepan and warm over low heat before tossing with your preferred pasta.