This recipe is from the same book I made the croissant egg casserole from (recipe # 18). It's amazing to me that you can create an entire cookbook of casseroles (or at least an entire section) with essentially the same ingredients. Hey, can't fault the author for having an amazing editor and an amazing publisher, clearly. Anyway, the concept is the same, obviously - eggs, some kind of bread and in this case -- leeks again (I'm still obsessed with them) and breakfast sausage.
You can't see the bread, but it provides the bottom layer and really helps make this casserole quite hearty. Again, it was easy, quick to assemble, and since I made it the night before, all I had to do was pop it into the oven in the morning. 4 stars.