01 - Grease a 9x13-inch baking dish thoroughly with butter or cooking spray.
02 - Scatter half of the English muffin pieces evenly in the prepared dish. Top with half of the Canadian bacon. Repeat layers with remaining muffins and bacon.
03 - In a large bowl, whisk together eggs, milk, salt, black pepper, Dijon mustard, and paprika until fully combined.
04 - Pour the egg mixture evenly over the muffin and bacon layers. Press gently with a spatula to ensure bread absorbs the liquid.
05 - Cover dish with plastic wrap or foil. Refrigerate for at least 1 hour, or overnight for optimal results.
06 - Preheat oven to 375°F.
07 - Remove casserole from refrigerator while oven heats. Bake uncovered for 40-45 minutes until center is set and top is golden brown.
08 - While casserole bakes, place egg yolks, lemon juice, Dijon mustard, salt, and cayenne in a heatproof bowl over simmering water. Whisk constantly while slowly drizzling in melted butter until thickened and smooth. Remove from heat.
09 - Let baked casserole rest for 10 minutes before slicing. Serve warm, drizzled generously with hollandaise sauce. Garnish with fresh chives or parsley if desired.