Preheat the oven to 400 degrees F. Line 2 sheet pans with parchment paper. Arrange 8 slices of bacon on each tray and bake until brown and crispy, about 12 to 15 minutes.
Fill a large deep-sided skillet 3/4 of the way up with water. Bring to a light simmer over low heat and add the vinegar.
Using a 3 1/2-inch biscuit cutter, cut out rounds from the center of each piece of toast. (Reserve the crust for the Round 2 recipe Savory Bread Pudding with Ham).
Crack the eggs, 1 at a time, into a small dish or ramekin and slide each into the lightly simmering water. Fan the egg white over the yolk with a slotted spoon if it begins to spread. Poach the eggs until the white is set but yolk is still runny in the middle, about 2 to 3 minutes, Remove the eggs to a towel lined plate to drain.
In a blender, combine the egg yolks, lemon juice, Worcestershire sauce, cayenne and a pinch of salt. Blend to combine, then turn the blender on and slowly pour the melted butter through the hole in the blender lid.
Put 2 slices of toast on each plate. Break the bacon strips in half and place 4 halves on each toast round, then top with a poached egg. Slowly pour the hollandaise over the top. Sprinkle each with chopped parsley and serve.