2Butter an 8-cup gratin dish and dust with the Parmesan. Cut out the chard stems, dice them, and set aside. Chop the chard leaves; you should have about 2 cups.
3Heat the olive oil in a cast-iron skillet over medium heat and sauté the diced chard stems and shallots until soft, 5 to 7 minutes. Add the chard leaves, arugula, herbs, and salt and pepper to taste. Sauté to wilt the greens, about 5 minutes. Remove from the heat and set aside.
