01 - Grease a 9x13-inch baking dish thoroughly. Scatter half the English muffin pieces evenly across the bottom. Layer with half the Canadian bacon. Repeat layers with remaining muffins and bacon.
02 - Whisk together eggs, milk, salt, black pepper, Dijon mustard, and paprika in a large bowl until fully blended. Pour evenly over the layered ingredients, pressing gently to help bread absorb the liquid.
03 - Cover the dish tightly with plastic wrap or foil. Refrigerate for at least 1 hour, or preferably overnight to allow flavors to meld and bread to fully soak.
04 - Set oven to 375°F and allow to fully preheat while preparing the hollandaise sauce.
05 - Create a double boiler by placing a heatproof bowl over a pot of gently simmering water. Whisk egg yolks, lemon juice, Dijon mustard, salt, and cayenne in the bowl. Slowly drizzle in melted butter while whisking constantly until thickened and smooth. Remove from heat and keep warm.
06 - Remove casserole from refrigerator while oven heats. Bake uncovered for 40 to 45 minutes until the center is set and top is golden brown.
07 - Let the baked casserole rest for 10 minutes before slicing. Serve warm, generously drizzled with hollandaise sauce. Garnish with fresh chives or parsley if desired.