How to Make It
Heat oven to 350° F.
Heat 1 tablespoon of the oil in a large skillet over medium-high heat. Add the chard and onion and cook until tender, 3 to 4 minutes.
In a medium bowl, beat the eggs with the half-and-half; season with 1 teaspoon salt and ¼ teaspoon pepper. Add the Cheddar and chard mixture and mix to combine. Pour into the prebaked 9-inch piecrust and bake until set, 40 to 45 minutes.
Meanwhile, in a medium bowl, toss together the lettuce with the vinegar, the remaining 2 tablespoons of oil, ½ teaspoon salt, and ¼ teaspoon pepper.
Serve the quiche with the salad.