Clean and cut the leeks into sections.

Melt the butter over low heat in a sauté pan, add the leeks, season with salt and pepper. Cook semi-covered for about 40 minutes, stirring occasionally.

Peel and cut the potatoes into pieces. Then cook them in a large pot of salted water for about 20 minutes.

Once cooked, mash them using a food mill, add the milk, butter, grated Gruyère cheese, salt, and pepper. Set aside to serve hot.

Once the leeks are cooked, stir in the heavy cream, mix a little to thicken, and set aside.

In a hot non-stick skillet, add a drizzle of olive oil, then place the scallops, previously salted and peppered. Sear them for 30 to 45 seconds, then turn the scallops over and lower the heat. Add a small amount of butter and let it melt and foam. Be sure to baste the scallops with the foaming butter. After one minute of cooking, remove the scallops and plate them!

On a plate, using a ring mold, place the mashed potatoes, then the leek fondue, and top with a scallop.