Boil cabbage in salted boiling water for about 5 minutes.
Throw in a colander and allow to drain excess water.
Put the cabbage in a greased, heat-resistant form. Pour 3 tablespoons of soy sauce.
In a saucepan, heat the butter, add the flour and bring over low heat until light Golden brown. Gradually pour the cream, stirring constantly to avoid lumps. Add mustard, salt and pepper. Boil for a few minutes.
Stir in 3/4 of grated cheese.
Pour the sauce over the cabbage. Mix the remaining cheese with breadcrumbs. Pour on sauce.
Bake in a preheated 180 degree oven for 40-50 minutes.