Spray the bottom of a 9x13” baking dish with cooking spray.
In a large bowl, toss together english muffin pieces and canadian bacon pieces, then pour into the 9x13” baking dish.
In the same large bowl, after it has been emptied, whisk together milk, eggs, onion powder, garlic powder, paprika, salt and pepper. Pour the english muffin mixture in the prepared baking dish. Cover and refrigerate overnight (or for 8 hours).
Preheat oven to 375℉. Cover with foil only and bake for 30 minutes. Remove the foil and bake for another 15 minutes until eggs are completely cooked through.
Cut into squares and serve warm topped with prepared Hollandaise sauce, chives, and an extra sprinkle of paprika (if desired).
Notes
Using day-old english muffins or slightly stale bread can help keep the casserole from getting too soggy.