Soak the brains from 2 calf’s heads in water for 15 minutes or more. Remove the membrane, boil the brains in salted water with a small amount of vinegar, and drain in a colander. After the brains have cooled, rub them through the colander, adding 1½ spoons melted butter, a little salt, pepper, nutmeg, and 5–6 egg yolks. Mix thoroughly and add the reserved egg whites, beaten until stiff. Transfer to a buttered mold strewn with rusk crumbs and bake in a hot oven for 30 minutes. To serve, pour on crayfish, mushroom, or rum sauce.