*The broccoli should be very finely chopped. I shave/chop the florets with a knife, then grate the stems on a cheese grater and use those too so I don't waste any. You could try using frozen broccoli, but you probably won't be able to cut it into such fine pieces. You can use other vegetables to replace the broccoli, but the casserole might be more watery.
If you don't want to use sausage patties, just use a layer of cooked crumbled sausage. You could even just mix this right in with the egg mixture.