Preheat oven to 425 degrees F.
Prep garlic for roasting: Cut ¼ inch of the whole garlic head from the top to expose some of the cloves. Do not peel it. Place it on aluminum foil, and generously drizzle with about 1 tablespoon of olive oil, ½ teaspoon salt and a few grinds of freshly ground black pepper. Fold up the foil and close tightly by twisting it from the top. Place it on a large sheet pan.
On the same sheet pan, toss the butternut squash and onions with a few drizzles of olive oil, and salt and pepper to taste. Roast the butternut squash, onions, and the prepared garlic for 30-35 minutes, or until vegetables are softened, turning midway through. You may need to remove the onions a few minutes early. Note: if your pan is too crowded, use 2 sheet pans.
Transfer the roasted butternut squash and onions to a large pot. For the garlic, remove the foil and squeeze out the garlic cloves into the pot. Add the broth and the thyme.
Blend everything until smooth with an immersion blender. Bring to a simmer to warm it up, and simmer for about 5-10 minutes. Add more broth if needed until desired consistency. Season with more salt and pepper to taste if desired. Note: if you don’t have an immersion blender, use a regular stand blender. You may need to do it in batches. Be careful when handling the hot veggies.
Serve immediately. I garnished it with pumpkin seeds, thyme, olive oil, and heavy cream. Enjoy!