Place the butter in cubes in a measuring cup, and melt in the microwave, for about 1 minute. After 30 seconds give it a stir.
In a blender add the eggs yolks, lemon juice, mustard, heavy cream, maple syrup, salt and pepper. Blend for 30 seconds, until the ingredients are well combined.
Slowly pour the butter in the blender with the others ingredients running on slow speed.
Mix for about a minute until you obtain a smooth, velvety texture.