Cook the chards in their own juice. Add some steamed potatoes according to taste. In a saucepan, heat olive oil and add two cloves of garlic and diced ham. Add a teaspoon of flour and cook over low heat. Drain the chards and pour the mix on top of them.
Drain the chards and place them in an oven dish. Heat olive oil and add chopped onion, diced ham and a teaspoon of flour. Cook over low heat and gradually add a glass of milk. Season, and when the sauce has thickened, pour it over the chards and cook au gratin in the oven.