Preheat your oven to 400°F (200°C). Toss the cauliflower florets and whole garlic cloves with olive oil, salt, and pepper. Spread them on a baking sheet and roast for 25-30 minutes.

Combine the roasted cauliflower, garlic, chopped tomatoes, and vegetable broth in a large pot. Bring to a simmer over medium heat for about 10 minutes.

Use an immersion blender to puree the soup until smooth. Alternatively, transfer to a standard blender in batches.

In a separate pot, bring water to a boil and add quinoa. Cook according to package instructions, about 15 minutes.

Ladle the warm soup into bowls and top with crispy quinoa and fresh herbs, if desired.