Put the egg yolks, juice from 1/2 lemon (approximately 1 Tablespoon), a couple dashes of hot sauce, and a pinch of salt in a blender. Blend briefly to combine.
Heat the butter in a large glass in the microwave until melted. Start with 30 seconds and heat an additional 10 seconds as needed. (Be careful, if left too long heating it will explode in the microwave).
Add the Parmesan cheese to the warm butter and stir to combine.
With the blender running on medium speed, slowly feed the butter cheese mixture into the blender feeding tube.
Continue processing until fully combined and volume has increased, approximately 30 seconds.
Season to taste with hot sauce, salt, and lemon as desired.
Hollandaise cannot be reheated in the microwave because it will scramble. I simply put it on top of warm food and it will quickly soften and return to a sauce state.It is best to use fresh Parmesan cheese as well as cheese that has been finely grated as it will more quickly integrate into the sauce with less bumps.