To make the hollandaise, add egg yolks, lemon juice and water to a blender. Blend to combine. With the motor running, slowly pour the lukewarm butter through the top of the blender to form a thick sauce. Season, cover and keep warm (see tip).
Meanwhile, bring a deep saucepan of water to a gentle boil. Reduce the heat to a simmer and add a dash of vinegar to the water. Crack each egg into a ramekin or cup, pour egg into simmering water then gently swirl the water with a spoon. Leave until the white is just beginning to set and carefully turn with a slotted spoon to form into an oval shape. Repeat with remaining eggs. Simmer for 3-4 minutes or until the white is just set and the yolk is soft in the middle. Keep an eye on the heat, if the water starts to bubble, turn it down to stop it disrupting the egg™s shape. Use a slotted spoon to remove the eggs to a plate lines with paper towel.
Top toast with ham, tomatoes, spinach and poached egg. Spoon over the hollandaise and sprinkle with remaining chives and pepper. Serve.