Wash and leave the potatoes whole.
Boil the potatoes in a large pot until just tender. You know they are ready when you can stick the potatoes with a sharp knife, and they feel soft. Cool the potatoes down under running cold water. Or you can get a large bowl of water with ice in it and cool them that way.
When you ready to make the smashed potatoes pre-heat your oven to 180°C fan bake.
Now smoosh the potatoes with the bottom of a glass or jar (don't push too hard). You want them to crack open, but still hold their shape.
Oil the potatoes. I like to use a great NZ based oil from The Good Oil.
Season with salt and pepper to taste.
Bake until crispy on the outside and until golden.
Roughly 5 minutes before they are ready, drizzle the garlic herb butter over the top of the potatoes. You could also leave this stage and once the potatoes come out of the oven, pop into a bowl and put a dollop of garlic and herb butter over the top. As the butter melts, toss the potatoes to evenly coat the potatoes.
Serve warm