Preheat the oven to 190 C / 375 F / 170 FAN / Gas 5 for
Start by grating the cheese and peeling and slicing the onions.
Cut the mushrooms into quarters and cut the bacon into chunky slices.
Heat the oil in a large pan and fry the onions and sausages together over a medium heat for about 10 minutes until coloured.
Add the bacon pieces and mushrooms and fry for a further 5 minutes.
Grease the baking dish with a little oil or butter.
While the sausage mixture is cooking spread the bread with the butter, slice in half or quarters and arrange in the baking dish.
Whisk together the eggs with the milk, seasoning and parsley.
Divide the sausage and bacon mixture evenly around the bread.
Pour over the egg mixture until all the bread is covered.
Sprinkle with the cheese.
Cook for about 25 minutes until puffed up and golden.