Step 1: In a non reactive saucepan combine the Verjuice, bay leaf and peppercorns. Place over a high heat and reduce to two tablespoons of syrup.
Step 2: Place the unsalted butter into a small pot and place over a high heat and cook for 5 to 6 minutes until nut brown, then remove from heat. The butter will turn nut brown at approximately 150C. Immediately remove from the heat, pour into a heat proof jug and leave for 5 – 6 minutes to cool a little.
Step 3: In the food processor combine the egg yolks with cooled Verjuice reduction and whiz to emulsify. Make sure the butter is quite warm – it needs to be about 70C. Whilst the food processor is running slowly pour in the warm nut brown butter to the egg mixture, like making a mayonnaise and till the thickness of one. Check seasoning and adjust.