Step 1: Roast the Garlic
Preheat your oven to 400°F (200°C). Slice the top off a whole bulb of garlic to expose the cloves. Drizzle with olive oil and wrap in aluminum foil. Roast for 35–40 minutes, or until the cloves are soft, golden, and fragrant. Let it cool slightly, then squeeze the roasted garlic out of the skins and set aside.

Step 2: Prepare the Cauliflower
While the garlic is roasting, chop the cauliflower into small florets. Toss them with a tablespoon of olive oil, season lightly with salt and pepper, and roast them on a baking sheet for 25–30 minutes until they’re golden and tender. Roasting enhances the flavor and adds a hint of sweetness to the soup.

Step 3: Sauté the Onions
In a large soup pot or Dutch oven, melt the butter over medium heat. Add the diced onion and sauté for about 5–7 minutes until translucent and fragrant. Stir in the roasted garlic cloves and thyme, cooking for another minute to combine the flavors.

Step 4: Simmer the Soup
Add the roasted cauliflower to the pot and pour in the vegetable broth. Bring the mixture to a boil, then reduce the heat and let it simmer for 10–15 minutes to allow all the flavors to meld together.

Step 5: Blend and Add Cheese
Use an immersion blender to puree the soup until smooth and creamy. Alternatively, blend it in batches in a countertop blender, being cautious with hot liquids. Once smooth, return the soup to low heat and stir in the heavy cream and shredded cheddar cheese. Continue stirring until the cheese is fully melted and the soup is creamy. Taste and adjust seasoning with additional salt and pepper if needed.