From America's Test Kitchen Season 10: Egg Dishes with an Accent
French onion tart is similar to quiche but delivers a more refined slice of pie, with more onions than custard. But re-creating this tart at home can produce a tough and crackery crust, which is doubly disappointing after spending long hours delicately cooking the onions, making the custard, and baking the whole thing together. We wanted to simplify the crust and shorten the overall preparation time.
We found that our onions would cook in half the usual time if we left the lid on the skillet throughout cooking. And covering the onions allowed them to cook entirely in their own juices, thereby becoming tender, retaining their pure onion flavor, and cooking more evenly. We liked bacon, which acted as a crisp foil to the creamy filling, but we found a traditional custard with the bacon to be simply too rich. To resolve the issue, we reduced the number of eggs and switched out the cream for half-and-half. And to ensure the bacon stayed crisp, we sprinkled it on top of the custard. We tried several classic crust recipes, looking for one that had the intense butteriness of traditional tart dough but could still be easily patted into a tart pan. We found that using a food processor to cut cold butter completely into the flour mixture required less ice water than a conventional crust, which kept the dough firm enough to press into the pan.
Serves 6 to 8
Either yellow or white onions work well in this recipe, but stay away from sweet onions, such as Vidalias, which will make the tart watery. Use a 9-inch tinned-steel tart pan. This tart can be served hot or at room temperature and pairs well with a green salad as a main course. Leftovers should be wrapped in plastic wrap and refrigerated. Reheat on a baking sheet in a 325-degree oven for 10 to 15 minutes.