We make that casserole for special breakfasts (thanksgiving, christmas, family visiting) but we call it a strata. I use a bag (or a part of a bag) of cubed stuffing, and the ingredient vary depend on who will be eating it; ie my son doesn't like mushrooms, my husband likes green peppers, etc - it's a very forgiving recipe that can be doctored. I like it best with a sage sausage - I'm not a big fan of limp bacon. It's never been greasy because I drain the sausage thoroughly. Probably one of my favorite comfort foods. I've never used frozen onions, good tip - I'll remember to throw them in with the sausage when it's browning if I decide to pick a bag up to make things easier.