Spray a 9x13 baking dish with non-stick cooking spray.
Place the cubed English muffins on a baking sheet and set under the broiler for a few minutes to get nice and toasty.
Take half of the toasted English muffin cubes and place them into the baking dish. Top with half of the Canadian bacon and 1 cup of shredded cheese. Repeat process, ending with the cheese.
In a medium mixing bowl, whisk together the eggs, half-n-half, salt, pepper, mustard, garlic powder, thyme, salt, and pepper. Pour the egg mixture over the cheese in the baking dish. Using a spatula, gently press down to make sure everything is well coated. Cover with plastic wrap and chill overnight.
When you're ready to bake preheat your oven to 375° F. Remove the casserole from the fridge at least 15 minutes prior to baking. Remove the plastic wrap and cover with foil. Bake covered for about 30 minutes, then uncovered for an additional 15 to 20 minutes, or until golden on top and a knife inserted into the center comes out clean.
While the casserole is in the oven, go take a sneak peek the parade, then go make the hollandaise sauce. In medium saucepan melt the butter over medium heat. Pour in the hollandaise packet mix and stir. Gently pour the 2/3 cup of water into the saucepan and keep whisking until the hollandaise sauce has thickened about 3 to 5 minutes. Set aside.
Remove the casserole from the oven and drizzle the hollandaise sauce. Garnish with paprika and fresh chives.
If you have time and real estate in your fridge, you can make this casserole at least 2 days in advance.