In a rondeau or similar pot, sweat the onions in the olive oil over moderate heat until very tender, about 5 minutes. Add the garlic, bay leaves, and red pepper flakes and continue to cook until fragrant, about 30 seconds. Add the cauliflower and sweat gently, stirring occasionally, for 5 minutes.
Crush the tomatoes and add, with their juice, to the cauliflower