Blanch the cauliflower in boiling salted water for about 4 minutes. Shock in ice water and then drain.
Rinse the tomatoes, cut into quarters and core.
Trim the spinach, rinse and shake dry. Arrange the cauliflower, tomatoes and spinach in a baking dish, pour the vegetable broth over top and cover with the cheese sauce. Sprinkle with Parmesan and bake in a preheated oven at 180°C (approximately 350°F) until golden brown, around 20 minutes.