cheddar cheese and onions soufflé

Guys, this may be the tastiest recipe I've ever made up. Seriously. It theoretically makes 6-8 servings, I think it made 4 for us. We couldn't stop eating it! The middles are so warm and gooey, the top so golden-brown and cheesy, there's nothing wrong with this recipe unless you're a gluten free, lactose intolerant, sad person.

1 day-old loaf grocery store French/Italian bread (the loafy kind, not a baguette)
6 oz shredded cheddar (reduced or low fat, if you have it)
2 c warm milk (also low fat)
1/2 tsp mustard powder
1/8 tsp cayenne pepper
3/4 tsp salt
1/2 tsp fresh ground black pepper
3 eggs, separated
1-2 Tbl butter
1/2 medium onion, finely diced
6 (or more) scallions/green onions, finely sliced

-preheat the oven to 450 F

-butter a casserole dish

-cut the bread into thick slices, tear off the crust and tear the bread into 1" or so chunks, place in a large bowl

-mix the egg yolks into the warm milk with all of the seasoning, pour over the bread and let soak while doing the remaining steps

-set 1 to 2 Tbs of butter in a frying pan, over medium heat

-finely dice 1/2 an onion and soften in the pan of hot butter until translucent, let cool slightly

-beat the egg whites to stiff peaks

-slice the scallions/green onions, keep separate

-mix softened onion and cheese into the milk/egg yolk/bread mixture

-in 3 additions, fold egg whites and green onions into the mixture

-pour into buttered casserole dish

-bake for 45 minutes, yes it will sink/deflate when you take it out of the oven. serve warm with salad and/or veggie burgers

inspired by: a Real Simple recipe