1. Heat butter in a medium skillet over medium heat. Add Canadian bacon, and cook until well browned on both sides. Divide bacon among the English-muffin halves.

2. Fill a large deep saucepan with 2 inches of water and bring to a boil. Reduce heat to medium. When water is barely simmering, break one egg into a small heatproof bowl. Placing lip of bowl in the water, gently tip the bowl to slide egg carefully into pan. Use a small spoon to "fold" the edges of the white over the egg, for a neater edge. Repeat with remaining eggs. Cook until whites are just set but yolks are still soft (they should still move around inside), 2 to 3 minutes. Lift out eggs with a slotted spoon or small mesh sieve; transfer to a paper towel-lined plate to drain. Trim edges of whites with a knife, if desired.

3. Gently place the egg on a bacon-topped muffin, and spoon the reserved warm hollandaise sauce over the top; serve immediately.