Preheat oven to 400ºF (204ºC) and line a baking sheet with parchment paper.
Arrange the garlic cloves, onion and cauliflower on the baking sheet. Drizzle with half of the olive oil, Italian seasoning and salt. Using your hand or a spatula, toss until vegetables are evenly coated in the spices. Roast for about 40 minutes or until very tender and caramelized, flipping halfway through.
When vegetables are just about done, heat remaining olive oil in a large soup pot over medium heat. Add the kale and 1/2 of the vegetable broth to the pot and cover. Let steam for 2 minutes, or until kale is wilted and tender.
Add the roasted vegetables and remaining vegetable stock in with the wilted kale. Bring soup to a gentle boil then remove from heat.
Puree soup in batches in a high-speed blender until smooth and creamy. Divide into bowls and enjoy!