Preheat oven to 325 degrees. Oil a 6-cup souffle mold. Roll 1/4 cups bread crumbs in it to coat the inner surface, knocking out excess crumbs.
Cook the onions slowly in the 1 tbsp butter for about 10 minutes in a covered saucepan, not allowing them to color.
Scrape the onions in to a 3 qt mixing bowl. Stir in the seasonings, cheese, and the 2/3 cups bread crumbs.
Beat in the eggs.
In a small saucepan, bring the cup of milk to a boil with the 4 tbsp butter.
In a thin stream of droplets, beat in the hot milk and butter.
Fold the cauliflower into the custard mixture.
Turn the custard into the prepared mold and set mold in a pan of boiling water. Place in lower third of preheated oven and bake for 35-40 minutes, regulating heat so water remains just below the simmer.
Custard is done when a knife plunged through the center comes out clean.
Remove mold from water and allow to settle for 5 minutes.
Run a knife around the edge of the custard and reverse on a warm serving platter. Surround with choice of sauces (Sauce au Cari) and serve.