Unlike a traditional quiche Lorraine, this crustless version is healthy and gluten-free. The luxury ingredient— smoked Gruyère cheese— and the caramelized onions enhance the rich, sweet, and savory flavor of this quiche. If you’re not an onion lover, please don’t exclude this step. You will be surprised that sautéing the onions brings out their natural sugars, and they won’t taste like the crunchy bitter vegetable you are used to. Below is a recipe that feeds 4 to 6 people.