In a large frying pan, sauté the onions in the oil for 8–10 minutes or until they are golden. Remove the onions from the pan and reserve half for the kasha and half for the sweet potatoes.

In the same pan (don’t wash it first!), combine the kasha with the egg white. Reserve the yolk. Cook this over a medium flame, stirring constantly, for about five minutes or until the kasha is dry and toasted.

Remove from the heat. Slowly add the hot water and vegetable soup mix to the kasha. Be careful as it can splatter. Return the pan to the fire, cover, and simmer for 15 minutes or until most of liquid is absorbed. Remove the kasha from the heat and let it stand, covered, for five minutes or until the liquid is absorbed. Fluff with a fork and cool slightly.

Combine the kasha with half the sautéed onions. Add salt, pepper, egg, and reserved egg yolk. Mix well. Spread the kasha mixture in the bottom of a 9- x 13-inch (22- x 33-centimeter) greased glass baking dish. Press down lightly and into the corners to form a base for the casserole.

Combine the other half of the sautéed onions with the sweet potatoes, eggs, oil, cornflake crumbs, sugar, salt, pepper, and nutmeg. Spread this evenly over the kasha layer.

Combine the topping ingredients in a small bowl and sprinkle evenly over the sweet potato layer. Bake in a preheated 350°F (180°C) oven for 45 minutes or until golden. It is ready when a knife inserted comes out clean. This casserole can be frozen.