Melt the butter in microwave or in a small pot over the stove. Allow the butter to begin to bubble, but not reach a full boil.
As butter is melting, add egg yolks and lemon juice into your blender. Blend at a medium to medium high setting until the egg yolk lightens to a light yellow color. This will take about 20-30 seconds.
Slowly drizzle the hot butter into your egg yolks while your blender is at the medium setting. Use a clean kitchen cloth to prevent any spatters of the hot butter onto you as you are pouring.
Add hot water as a final step in blending your hollandaise sauce.
If you prefer your hollandaise sauce a bit thinner, add hot water a tablespoon at a time, pulsing after each addition until the hollandaise reaches the consistency you prefer.
You may add more lemon juice if you prefer more lemon flavor in your hollandaise, as well.
Add a pinch of cayenne pepper to final hollandaise sauce (optional)