Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish with cooking spray or butter.
In a large bowl, combine the torn English muffins and chopped Canadian bacon. Spread this mixture evenly in the prepared baking dish.
In another bowl, whisk together the eggs, milk, Dijon mustard, salt, and black pepper until well combined.
Pour the egg mixture over the English muffin and bacon layer, ensuring all pieces are soaked.
Sprinkle the shredded cheddar cheese and chopped chives evenly over the top.
Cover the dish with aluminum foil and let it sit for 30 minutes to allow the muffins to absorb the egg mixture.
Bake covered for 30 minutes, then remove the foil and bake for an additional 15-20 minutes, or until the casserole is set and golden on top.
Allow to cool for 5-10 minutes before serving. Drizzle with hollandaise sauce before serving.