Mince the Shallot (3).
In a small saucepan over medium heat, melt 1 Tbsp of Unsalted Butter. Once melted mix in shallots, Salt and Pepper (to taste). Measure White Wine Vinegar (2 tablespoon) into the pan and cook until the liquid has evaporated.
Lower the heat and continue cooking for 5 minutes, stirring occasionally. Empty mixture into a bowl and allow to cool.
Over medium heat, melt Unsalted Butter (1 cup). Once foamy, pour into a small bowl.
Whisk together yolks of the Egg (2), Lemon Juice (1 tablespoon), and Warm Water (1 tablespoon). Once combined, slowly add the melted butter. Mix until creamy, about 2-3 minutes.
Mince the Fresh Rosemary (1 tablespoon). In a medium bowl combine egg mixture with shallot reduction and rosemary. Taste and add more Salt and Pepper (to taste) if needed. Serve immediately over eggs, steak, roasted vegetables, or any other desired foods!