1. Start by making the Hollandaise sauce. In a heatproof bowl, whisk together egg yolks and lemon juice until the mixture is thickened and doubled in volume.
2. Place the bowl over a saucepan of simmering water (not boiling). Continue to whisk rapidly. Be careful not to let the eggs get too hot or they will scramble.
3. Slowly drizzle in the melted butter while continuing to whisk until the sauce is thickened and doubled in volume. Remove from heat and whisk in cayenne and salt. Cover and keep warm.
4. In a large saucepan, bring water to a gentle simmer. Add a splash of vinegar. Crack eggs one at a time into a small bowl and gently slide into the water. Poach for about 3-4 minutes, until whites are set but yolks are still runny. Remove with a slotted spoon and drain on paper towels.
5. While eggs are poaching, toast the gluten-free English muffins and warm the Canadian bacon in a skillet over medium heat.
6. To assemble, place two muffin halves on each plate. Top each half with a slice of Canadian bacon, a poached egg, and a generous spoonful of Hollandaise sauce. Serve immediately.