01 - Grease a 9x13-inch baking dish. Scatter half of the English muffin pieces evenly in the dish. Top with half of the Canadian bacon. Repeat with remaining muffins and bacon.
02 - In a large bowl, whisk together the eggs, milk, salt, black pepper, Dijon mustard, and paprika. Pour the mixture evenly over the muffin and bacon layers. Press gently to ensure the bread absorbs the egg mixture.
03 - Cover and refrigerate for at least 1 hour, or overnight for best results.
04 - Preheat oven to 375°F.
05 - Remove casserole from the refrigerator while the oven heats. Bake, uncovered, for 40–45 minutes, until the center is set and the top is golden.
06 - While the casserole bakes, prepare the hollandaise sauce: In a heatproof bowl over a pot of gently simmering water, whisk together egg yolks, lemon juice, Dijon mustard, salt, and cayenne. Slowly drizzle in melted butter, whisking constantly until thickened and smooth. Remove from heat.
07 - Let the baked casserole rest for 10 minutes. Slice and serve warm, drizzled generously with hollandaise sauce. Garnish with fresh chives or parsley if desired.