Melt the butter in a small saucepan over low heat. In a heatproof bowl, whisk the egg yolks, lemon juice, and cold water until light and foamy, then place the bowl over a saucepan of simmering water (creating a double boiler).

Continuously whisk the egg yolk mixture over the simmering water until it thickens and coats the back of a spoon. Slowly drizzle in the melted butter while vigorously whisking until the sauce is thick and emulsified.

Remove the hollandaise from the heat and season with salt and pepper to taste; keep warm while you prepare the remaining components.

Fill a medium saucepan with about 3 inches of water and bring it to a gentle simmer; add a splash of white vinegar if desired. Carefully crack each egg into a separate small ramekin or bowl.

Gently slide each egg into the simmering water and poach for 3-4 minutes, or until the whites are set and the yolks are still runny. Remove the poached eggs with a slotted spoon and drain any excess water on a paper towel-lined plate.

While the eggs are poaching, toast the English muffin halves until golden brown and lightly pan-fry or warm the Canadian bacon slices. To assemble, place two toasted muffin halves on each plate and top with Canadian bacon.

Carefully place a poached egg on top of each slice of Canadian bacon, then generously spoon the warm hollandaise sauce over the eggs. Serve immediately and garnish with a sprinkle of paprika or chives, if desired.