Potatoes: 1.75 kg (peeled, diced).
Butter: 75 grams.
Milk: 600 ml.
Flour: 60 grams.
Olive oil: 2 tbsp.
Onions:1 (medium size, peeled and finely chopped)
Parmesan cheese: 100 g (grated).
Fish fillet: half a kilo.
Directions to prepare
The oven is heated to a temperature of 190 ° C.
To prepare the potatoes: Add the potatoes to a saucepan, submerge them in water, and boil for a quarter an hour after water boiling.
Drain the potatoes well, and mash.
Whisk the potato puree, with butter (30 grams) and milk (two tablespoons of it).
Add the remaining amount of milk to a saucepan over the fire, add then butter and flour, wait until the milk boils, then whisk until the consistency of the mixture thickens and take off the fire.
To prepare the fish pie
Heat the oil in a frying pan (without boiling), and stir the onions until tender, then sprinkle salt and black pepper as desired.
Add the mixture of milk, butter, and flour, and let it boil once with onions on a low heat.
Pour lemon juice, add mustard, and cheese.
Add the milk mixture with the ingredients of the fish pie and fish fillet to a special oven dish. Add the potato puree on the surface.
Cook in the hot oven for twenty-five minutes, noting that the potatoes are golden in colour.