Wash the cod fillet, dry it, season with salt and spices. Sprinkle with lemon juice. Roll up the rolls and place them in a baking dish. Leave while the sauce cooks.

Add flour to cold milk. Stir well with a whisk so that there are no lumps. Put on fire. Bring to a boil, stirring constantly. Cook over low heat, stirring constantly. Add butter and spices to taste. The thickness of the sauce should be like custard.

Pour the hot sauce into the fish pan. Bake in an oven preheated to 220 degrees for about 20 minutes.

Grate the cheese on a coarse grater. After 20 minutes, remove the fish and sprinkle with cheese. Return the fish to the oven for another 10 minutes.