Any of the breakfast strata recipes would work nicely:
Layer the bottom of a greased 8x8 casserole with your choice of browned sausage, crumbled cooked bacon, ham or if you don't do meat use sliced tomatoes and/or mushrooms.
Over that sprinkle 2 cups shredded cheese - cheddar is good, but jack, colby or goat cheese (crumbled) work fine too. Mozzarella gets a little stringy but you can use it.
Next layer is toasted bread - as many slices as it takes to cover the stuff underneath. If you use sourdough (sliced about 1/2" thick) you don't have to toast first.
Lightly whisk 6 eggs - maybe 4 duck eggs? - with a bit of milk, salt & pepper (or a dash of hot sauce) and pour over everything else.
Let sit covered in the fridge overnight and bake at 375 until puffed and lightly browned and a knife stuck in the center comes out clean.
Let cool a bit before slicing into squares to serve.