Roast your pickled garlic as per the instructions in that recipe. You can make this ahead of time if you like.
Boil the potatoes in a large pot of well salted water. You can leave them whole or peel and slice them into even sized chunks. Allow them to cook until they’re absolutely 100% cooked through – a knife should slide through the thickest potato with ease. The cooking time will heavily depend on how large your potatoes are.
While you’re waiting, measure out the butter and pour the milk into a small pot. Add the cooked garlic and allow the milk to infuse.
Once the potatoes are cooked, remove them from the water and allow them to come to a hand comfortable temperature.
Place the pot of milk over a very low heat and allow the milk to warm through. This has rthe added bonus of infusing the milk with even more garlic flavour.
Peel off the skins if you haven’t already, then place the peeled potatoes in a large bowl and mash with them a potato masher or put them through a potato ricer. I love my potato ricer so much but I know not everybody has one.
Add the cubes of butter and keep stirring to combine. Add splashes of the warmed milk at a time until you achieve the right consistency. I always use the full 250ml, but if need less simply retrieve the garlic bits from the milk and add them to the mash.
Add the (optional) sour cream, if you are using it.
Stir to combine and taste and adjust for seasoning, adding as much salt as necessary to achieve a full flavoured mash.
For best results, serve immediately. Serve as is or with an optional sprinkle of chives on top.