Preheat the oven to 350°F. Grease a 9x13-inch baking dish.
Cut the toasted English muffins into quarters and evenly distribute them in the prepared baking dish.
In a large bowl, whisk together the eggs, milk, salt, black pepper, garlic powder, and onion powder until well combined. Pour the egg mixture over the English muffins, ensuring they are all soaked.
Sprinkle the crumbled bacon or Canadian bacon evenly over the top, followed by the shredded cheddar cheese and chopped chives.
Cover the baking dish with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 15-20 minutes, or until the eggs are set and the top is lightly golden.
While the casserole is baking, warm the hollandaise sauce according to package instructions or your homemade recipe.
Once baked, let the casserole cool for 5 minutes before serving. Drizzle with hollandaise sauce before serving.