01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish with cooking spray or butter.
02 - Distribute English muffin pieces evenly across the prepared dish. Scatter diced Canadian bacon over the top.
03 - Whisk together eggs, milk, salt, and black pepper in a large bowl until fully blended. Pour mixture evenly over the muffins and bacon.
04 - Cover tightly with aluminum foil. Refrigerate for at least 1 hour, preferably overnight for optimal flavor absorption.
05 - Remove casserole from refrigerator while oven preheats. Sprinkle paprika evenly over the surface.
06 - Bake covered for 30 minutes. Remove foil and continue baking for 15–20 minutes until center is set and top is golden brown.
07 - Set a heatproof bowl over a pot of gently simmering water. Whisk egg yolks, lemon juice, salt, and cayenne for 2–3 minutes until slightly thickened. Slowly drizzle in warm butter while whisking constantly until sauce becomes thick and glossy. Remove from heat.
08 - Let casserole stand for 10 minutes before cutting. Serve slices topped generously with warm hollandaise sauce.