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 to create two complete layers.
02 - In a large bowl, whisk together the eggs, milk, salt, black pepper, Dijon mustard, and paprika until fully combined. Pour the mixture evenly over the muffin and bacon layers. Press gently with a spatula to ensure the bread absorbs the egg mixture.
03 - Cover the dish with plastic wrap or aluminum foil. Refrigerate for at least 1 hour, or overnight for best results to allow flavors to meld.
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 brown.
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 before slicing. Serve warm, drizzled generously with hollandaise sauce. Garnish with fresh chives or parsley and additional black pepper if desired.