Our family always has what we call a quickie on special occasions like Christmas morning so we can talk, open presents, have coffee and breakfast is done in 30 minutes because we made it the night before.
Spray a 9x13 pan lay 1/2 sliced bagels in bottom of pan and save the rest.
Chop bacon in small pieces and fry in skillet. When bacon almost done saute onions with bacon. Pour bacon mixture over bagels and cover this with 2 cups cheese and remaining bagels.
Whisk together eggs, parsley, milk, salt and pepper. Pour mixture over bagel layers and top with remaining cheese. Cover with foil and refrigerate 8 hours or overnight. In morning preheat oven to 400* and bake for 30 minutes until eggs are firm.