Boil the cabbage in salted boiling water for about 5 minutes.
Flip it into a colander and let the excess water drain.
Put the cabbage in a greased heat-resistant form. Pour in 3 tablespoons of soy sauce.
In a saucepan, heat the butter, add the flour and bring over low heat to a light golden color. Gradually pour in the cream, stirring constantly so that there are no lumps. Add mustard, salt and pepper. Boil for a few minutes.
Add 3/4 of the grated cheese.
Pour the sauce over the cabbage. Mix the remaining cheese with the breadcrumbs. Pour over the sauce.
Bake in a preheated 180 degree oven for 40-50 minutes.