Melt 225g butter over low heat. Skim the foam from the surface. Pour the clear golden liquid into a separate jug, leaving the milk solids in the pan.
Whisk 3 egg yolks and 1 tbsp cold water in a heatproof bowl over barely simmering water for 3 to 4 minutes until pale, thick, and tripled in volume.
Remove the bowl from the heat. Drizzle in the clarified butter drop by drop while whisking, increasing to a thin stream once the sauce is visibly thick. Add lemon juice, cayenne, and salt.
Set the bowl back over warm water off the heat. Whisk occasionally to keep it smooth.
Bring 1 litre water and 2 tbsp white wine vinegar to a gentle simmer (82 to 85°C / 180 to 185°F).
Crack each egg into a cup. Create a gentle swirl in the water. Slide the egg into the center and cook 3 minutes for a runny yolk. Drain on a kitchen towel. Work in batches of 2 to 3.
Cook Canadian bacon in a skillet over medium-high heat, 1 to 2 minutes per side until the edges are lightly browned.
Toast English muffin halves cut-side down until golden, about 2 minutes.
Assemble: muffin half, one slice Canadian bacon, one poached egg, 2 to 3 tbsp hollandaise. Finish with paprika and fresh chives. Serve immediately.
