Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

Place the cauliflower florets on the prepared baking sheet. Drizzle with 1-2 tablespoons of olive oil, season with salt and pepper, and toss to coat evenly.For the garlic, peel away the outer papery layers, leaving the skins of the individual cloves intact. Cut ¼ inch off the top of the garlic head, exposing the tops of the cloves. Place the garlic on a sheet of foil, drizzle with olive oil, and loosely wrap the foil around it. Place the foil-wrapped garlic on the baking sheet with the cauliflower.Roast for 30-35 minutes, flipping the cauliflower halfway through, until the cauliflower is golden brown and caramelized.

While the cauliflower and garlic are roasting, heat 1 tablespoon of olive oil in a pot over medium heat. Add the diced onion and sauté for 5-8 minutes until the onion becomes translucent.

Once the cauliflower and garlic are done roasting, add the sautéed onion, roasted cauliflower, roasted garlic (squeezed from the skins), broth, salt, and pepper to a blender. Blend until smooth, about 1 minute. Pour the blended soup back into the pot and place over medium heat.

Bring the soup to a light simmer, then stir in the shredded cheddar cheese. Continue to simmer for 10-15 minutes, stirring occasionally. Taste and adjust seasonings as needed.

Garnish the soup with sliced green onions and extra cheddar cheese. Serve with crusty toasted sourdough bread or your favorite bread for dipping.