1) Gather the milk and 25 g of butter in a thick-bottomed saucepan over low heat. When the butter has melted, add the sifted flour. Mix well: the mixture must be very thick and dry and collect in a ball in the center of the saucepan. Let it cool for 1-2 hours. Prepare one bechamel, dissolving the butter in a water bath in a saucepan. Incorporate the sifted flour, stirring. Put the saucepan on the stove and pour the cold milk, everything at once. Stir, adjust by salt, pepper and nutmeg and continue cooking for 5-6 minutes, always stirring.

2) Incorporate the remaining softened butter into the quenelle mixture eggs and the chopped fish. Salt and pepper (for a more homogeneous result, mix everything in the mixer). Leave the quenelle mixture in the fridge for at least 2 hours.

3) Bring to an abundant boil salt water in a pot. Make the quenelles (see box) and slide them into boiling water, one at a time. Proceed until the dough is finished, letting the quenelles slide into the boiling water. Cook for about 15 minutes or until the quenelles swell and rise to the surface. Drain them with a slotted spoon and place them in an ovenproof dish, spaced apart. Cover with a generous layer of béchamel and bake in a preheated oven at 200 ° for 10-12 minutes. Serve immediately.