Briefly cook the cauliflower in the broth and vinegar. In 2.5 cups of the cauliflower stock, cook the rice until it is grainy. Heat the flour in a pan without fat. Let cool, then add 3 ladles of cauliflower stock and bring to the boil.
Add butter, Roquefort and the cooked rice too. Stir in the egg yolks and the whipped egg whites. Season if necessary.
Pour the mixture into a greased casserole dish, place the cauliflower in the middle, drizzle with the melted butter. Bake in the oven at 200 ° C for 20 minutes. Serve sprinkled with cheese.