Gratin de Cardons

Cardoons

 * 2 to 3 cardoon heads, about 4 lb.
 * 1 whole lemon
 * large piece stale bread
 * 4 to 5 tbsp vinegar

Court Bouillon

 * 4 qt. water
 * 1 large onion, finely sliced
 * 2 to 3 bay leaves
 * 1 large sprig thyme
 * 1½ tbsp wine vinegar
 * salt to taste

Béchamel

 * 3 tbsp unsalted butter plus extra for topping
 * 1 onion, diced
 * 4 tbsp all-purpose flour
 * 4 cups whole milk
 * 1 whole clove
 * ½ tsp granulated sugar
 * 1 bouquet garni
 * 2 tbsp heavy cream, optional
 * pinch ground nutmeg
 * salt to taste
 * 6 tbsp freshly grated Parmesan cheese

Cardoons

 * 1) Cut off bases, and discard tough outer stems.
 * 2) Trim remaining stems, removing strings, leaves and prickles.
 * 3) Quarter hearts lengthwise.
 * 4) Wash and slice stems into 3- to 4-inch pieces, and rub with lemon to prevent discoloration.

Court Bouillon

 * 1) Combine ingredients in stockpot over medium heat, and bring to a boil.
 * 2) Place cardoon stems and hearts in pan with crusty stale bread to help remove bitterness of cardoons.
 * 3) Cook 15 to 20 minutes, remove from heat and cool.
 * 4) When cool enough to handle, lift edge of each piece with paring knife, and peel off skin.
 * 5) Trim away toughest fibrous strings down to tender stems.
 * 6) Soak trimmed cardoon pieces in water to cover with several tablespoons vinegar until ready to use.

Béchamel

 * 1) Melt butter in heavy saucepan over low heat.
 * 2) Add onion, and cook until pale golden.
 * 3) Add flour, and stir well, about 1 minute.
 * 4) Slowly add 1 cup milk, stirring constantly, and continue cooking 35 minutes more.
 * 5) When sauce thickens, slowly add more milk until all milk is used up.
 * 6) Add clove, sugar and bouquet garni.
 * 7) Continue to cook 1½ hours, stirring and scraping occasionally.
 * 8) Whisk sauce, and strain, removing bouquet garni and clove.
 * 9) Add heavy cream, if desired, and a pinch nutmeg and salt to taste.
 * 10) Preheat oven to 450 °F.
 * 11) Lightly butter ovenproof baking dish.

Assembly

 * 1) Place cardoons in baking dish.
 * 2) Add béchamel to cover evenly.
 * 3) Sprinkle uniformly with freshly grated Parmesan cheese and small pieces of butter for topping.
 * 4) Bake 5 to 10 minutes, or until golden.
 * 5) Remove from oven, and serve.