Fish Roll with Spinach Filling

	Heat the milk. Sift the flour into a separate bowl along with salt, pepper, and nutmeg. Add the yolk. Gradually pour in the warm milk and softened butter, thoroughly mixing the batter with a whisk. Switch to a saucepan and, whisking continuously, warm over low heat until the mixture begins to pull away from the sides.
	Place the white fish fillet in a blender and blend until smooth. Pour in the cooled flour mixture and the egg white, then whip the cream and gently fold it into the mixture. Place the puree in the refrigerator.
	Blanch the green beans in boiling salted water for a few minutes. Transfer to a colander, then mash into a puree. Mix with the yolk, breadcrumbs, and 2 tablespoons of the fish puree. Stir and chill in the refrigerator for about 30 minutes.
	Grease a baking dish with oil and line it with paper. Spread half of the fish puree on the bottom. Use the rounded side of a spoon to make a groove along the length of the dish.
	Cut the salmon fillet into thin strips and lay them across, slightly overlapping. Fill the groove with the bean filling in a cylindrical shape.
	Fold the edges of the salmon over the filling. Top with the white fish puree. Cover with a piece of parchment paper greased with oil. Bake in a preheated oven at 180 °C for one hour. Allow to cool, gently remove from the dish, and slice into portions.