Sausage and Leek Breakfast Casserole

Chef notes

Making a casserole for Christmas morning works so well because you can assemble it the night before, pop it in the fridge and in the morning, all you have to do is put it in the oven!

Technique tip: Allowing this to set overnight ensures the custard soaks into the bread perfectly, and the interior develops a soufflé like texture as it bakes.

Swap option: Replace the bread with any you have on hand, same with the sausage, Italian sausage works great here too! And if you don't have leeks, use a large yellow onion instead.