Preheat the oven to 350°F. Grease a 9x13-inch baking dish with cooking spray.
In a large bowl, whisk together the eggs, milk, Dijon mustard, salt, black pepper, and cayenne pepper until well combined.
Add the torn English muffins and chopped Canadian bacon to the egg mixture. Stir gently until the muffins are fully coated.
Pour the mixture into the prepared baking dish, spreading it evenly. Sprinkle the shredded cheddar cheese and chopped chives on top.
Cover the dish with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 15-20 minutes, or until the casserole is set and lightly golden on top.
Let the casserole cool for about 10 minutes before serving. Drizzle with hollandaise sauce before serving.