Preheat oven to 400 degrees.
On a baking sheet, spread cauliflower florets, onions, whole garlic cloves, salt, and pepper, and drizzle with enough olive oil to lightly coat the cauliflower and garlic. Gently toss on the baking sheet.
In the middle of the oven, bake cauliflower, onions, and garlic for 8 minutes, toss, and return to the oven for another 8 minutes.
Cook until the cauliflower is very tender. Check to avoid burning. The cauliflower should be a deep golden brown color and even a little burnt on the edges.
Transfer half of the cooked cauliflower mix to a blender and add one quart of stock. Blend until smooth. Depending on how thick you like your soup, add more stock until you get to your desired consistency.
Add the blended soup to a large stock pot and add the bay leaf.
Repeat the blending step with the remaining half of the cauliflower mix and one quart of stock.
Add blended soup to the stock pot, stir, and cook for 30 minutes. Season to taste.