Preheat oven to 375°F (190°C).

Peel and julienne cut the raw potatoes.

Cut up onions and sauté them until softened.

Cut up the sweet anchovy fillets.

In an oblong baking dish, create the first layer with half of the potatoes.

Spread half of the sautéed onions over the potatoes.

Distribute half of the cut anchovy fillets over the onions.

Sprinkle pepper to taste.

Repeat layers of potatoes, onions, and anchovies.

Sprinkle pepper to taste on the second layer.

Pour heavy cream over the mixture, ensuring it penetrates the layers.

Bake in the preheated oven for 1 hour, or until potatoes are tender and the top is golden brown.