Add the fridge cold double cream to the bowl of a stand mixer fitted with the whisk attachment. Start mixing on a medium speed. During the first stage the cream will thicken and become softly whipped. At this point it looks like pillowy whipped cream and holds gentle peaks.

Continue whisking and slowly increase the speed to medium-high. The cream will become stiffer and slightly grainy as the fat begins to clump together. keep mixing and you will see the magic happen. The butter will suddenly separate from the liquid in the sloshing stage, at this stage, cover the stand mixer bowl with a tea towel or guard to prevent spilling and turn down speed a little if you need. The solids will clump onto the whisk and the pale liquid left behind is buttermilk.

Once the butter has fully formed, stop the mixer. Remove the butter from the whisk and gently squeeze it to release as much buttermilk as possible. You can save the buttermilk for pancakes, baking, or marinades. Transfer the butter into a bowl of ice cold water or very cold water. Press and rinse the butter to wash away any remaining buttermilk.

Remove the butter from the water and place it into a clean bowl. Add the chopped herbs, garlic, and sea salt. Stir until everything is roughly and evenly distributed. Taste the butter before shaping. Adjust salt or garlic while it is still soft, as flavours mellow once chilled. Spoon the butter onto parchment paper and flatten it into a neat rectangle. Shape it tightly, then slice into portions if you like.

Wrap each piece in parchment paper and secure with string or tape. Stored in the fridge, this garlic and herb butter will keep well for around one week. You can also freeze it for several months, making it perfect for last minute flavour boosts.