Recipe for Swiss chard and potato gratin in béchamel sauce.

Prepare the Swiss chard. Wash it thoroughly, separating the green leaves from the white stems. Using a small knife or a peeler, lightly peel the white stems from top to bottom to remove the strings from the first layer (like with rhubarb). Cut the stems into small strips. Roughly chop the green leaves.

Cook the potatoes in a pot of boiling salted water for 30 minutes. Bring salted water to a boil in a saucepan. Dip the chard stalks in for 10 minutes. Drain them. Bring salted water to a boil in another saucepan. Add the green leaves for 5 minutes. Drain them. Preheat the oven to 200°C (400°F).

Peel and chop the onion and garlic. In a pan, melt 20 grams of butter. Add the onion and garlic and sauté for 2 minutes over medium heat. Prepare the béchamel. In a small saucepan, melt 40 grams of butter with the flour. Stir with a wooden spatula until a smooth paste forms (1 minute). Remove the saucepan from the heat and add the cold milk all at once. Mix immediately and vigorously with a whisk. When there are no lumps left, return the saucepan to low heat. Continuously stir with the whisk until the béchamel thickens well. Add pepper, nutmeg, and salt. Remove from heat. Then add the grated cheese and mix again until it melts well. Taste and adjust the seasoning.

Butter a baking dish. Place the garlic and onion mixture in it, then add the potatoes. Pour in a bit of béchamel, then cover with the ribs and finally the Swiss chard leaves.

To finish, pour the remaining béchamel over everything. Bake for about 30 minutes. Let cool for 2 minutes and serve. Enjoy your meal!