Preheat oven to 400°F (200°C). Toss cauliflower florets with 2 tablespoons olive oil, salt, and pepper. Roast for 20-25 minutes, or until tender and slightly browned.

While cauliflower is roasting, prepare the garlic. Wrap garlic cloves in foil and roast for the last 10-15 minutes of the cauliflower's cooking time.

In a pan, heat 2 tablespoons olive oil. Add chopped onion and cook on medium-high heat until translucent.

Squeeze garlic out of skin and add to a blender. Add onion, cashews, roasted cauliflower (saving some for garnish, if desired), vegetable broth, and tamari. Blend until smooth and creamy. Pour mixture into a deep pan and bring to a boil. Reduce to a simmer, and cook for 10 minutes. Add salt and pepper to taste.