Preparation

• Position a rack in the center of the oven and heat to 350°F. Butter a 9×13-inch or similar 3-quart baking dish.
• 修剪韭菜，留下白色和浅绿色的部分。切成一半的切片，然后横向切成1/2英寸厚的半月片，以产生约8杯。冲洗好，然后拍干。
• In a large skillet, heat the butter over medium heat. add the leeks, half of the chives, 1/4 tsp. salt, and 1/4 tsp. pepper. Cook, stirring occasionally, until the leeks are very tender but not browned, 8 to 10 minutes. Allow to cool slightly.
• Meanwhile, in a large bowl, whisk the milk, eggs, mustard, zest, the remaining chives, 1/2 tsp. salt, and 1/4 tsp. pepper. Add the bread, cheese, ham, and the leek mixture, and toss well. Transfer to the prepared dish and bake until golden brown around the edges and set in the center, 50 minutes to 1 hour. Let rest 10 minutes before serving.