Ingredients:
1 lbs Swiss chard
2 lbs medium sweet potatoes, peeled
2 Tbsp of butter
1 small onion, finely chopped
pinch of freshly grated nutmeg
salt and pepper to taste
1 Tbsp fresh parsley, minced
1 Tbsp fresh thyme, minced
1 ¼ cups (about 5 oz) Gruyere cheese, coarsely grated
2 cups heavy cream or whole milk
2 garlic cloves, minced
2 Tbsp of butter
2 Tbsp flour
Directions:
- Preheat oven to 400°. Separate Swiss chard leaves and stems, and chop both into ½ inch pieces. Slice the peeled sweet potatoes into rounds about ⅛ inch thick.
- Begin by sautéing chard stems in a small amount of oil, adding the leaves after about 5 minutes. Season with salt to help draw the moisture out of the greens. Stir often, until all parts are tender but not browned, about 8 minutes. Transfer to colander and press with a spatula or spoon to express excess water from the chard. It is important to remove as much liquid as possible!
- Heat 2 Tablespoons of the butter in a large, heavy pot over medium-low heat, and cook the onion, stirring, until softened. Season with nutmeg, salt and pepper. Assemble the roux by adding 2 Tablespoons flour to this mixture, and cook for about 1 minute. Slowly whisk in warm milk or cream, adding more as the mixture begins to thicken. Bring the sauce to a gentle simmer, whisking constantly, and cook about one minute, then remove from heat. Separate 1½ cups of the béchamel for layering and mix the drained Swiss chard mixture into the remaining sauce.
- Butter a 9” x 13” baking dish. Spread the chard and béchamel mixture in the bottom of the pan. Sprinkle with salt, pepper, the herbs and ¼ of the cheese. Then layer the thinly sliced sweet potatoes, alternating with the remaining béchamel, cheese and herbs until all are used.
- Bake the gratin for about 1 hour until golden and bubbly, and most of the liquid has been absorbed. Let stand for 15 minutes before serving.
Adapted from smittenkitchen.com