This savory tart recipe is perfect for the holidays and easy to make. You can either make it in a 9-inch tart pan or in a pie dish. It has tons of chunky ham, lots of gooey melty cheese, and caramelized onions, covered in a creamy egg custard with herbs baked in a crunchy, flaky pie dough. You could also substitute crispy bacon or prosciutto for the ham, and use any melty cheese you like. The caramelized onions and garlic give it a tangy sweet flavor that goes perfect with the cheesy creamy custard.