Preheat the oven to 425 degrees F.
Butter a 9x13-inch baking dish.
Arrange the English muffins on a rimmed baking sheet and bake until they are golden-brown, about 10 minutes.
Let the muffins cool.
In a large bowl, combine the 12 eggs, the milk, the half-and-half, 1 teaspoon of the salt, and 1/2 teaspoon of the pepper and whisk to combine.
In a large skillet over medium-high heat, heat the olive oil.
Add 1/2 of the Canadian bacon slices in a single layer to the skillet and cook until they are browned, about 1 minute per side.
Transfer the cooked bacon to a plate and repeat with the remaining bacon slices.
Add 1/2 of the spinach to the pan and toss until it is partially wilted, then add the remaining spinach and toss until all of it is wilted.
Season the spinach with the extra salt and transfer it to a paper-towel-lined plate and press with the back of a spoon to release some of the liquid.
In the prepared baking dish, layer 1/2 of the English muffins, 1/2 of the spinach, 1/2 of the bacon, and 1/2 of the cheese.
Repeat the layers with the remaining ingredients, starting with the English muffins and ending with the cheese.
Slowly pour the egg mixture over the bacon mixture.
Cover the dish with plastic wrap and refrigerate overnight.
Preheat the oven to 425 degrees F.
Transfer the egg mixture from the fridge 30 minutes prior to baking.
Replace the plastic wrap with foil and bake the egg mixture for 30 minutes.
Uncover the dish and bake until the egg mixture is golden-brown and slightly crisp on top, about 25-30 minutes.
While the egg mixture is baking, in a small saucepan, melt the butter until it is sizzling.
Transfer the saucepan from the heat.
Add the remaining egg yolks and the lemon juice to a blender and blend, while slowly drizzling with the yolk mixture, until the mixture thickens.
Add up to 1 1/2 teaspoons of the water to the egg mixture until the sauce is pourable.
Stir the salt, the pepper, and the hot sauce into the sauce mixture.
Drizzle some of the sauce over the bake.
Serve the bake with the remaining sauce.