Preheat the oven to 200 degrees celsius.
Cut the top off the head of the garlic and place into a small oven proof pot with a lid or into a sheet of alfoil. Drizzle with olive oil and season with a pinch of salt and pepper. Cover and bake for 1 hour. Allow to slightly cool and squeeze the garlic cloves out of their skin. Set to the side.
Place the potatoes into a large pot and cover with heavily salted cold water. On a high heat, cook for 30 - 40 minutes or until they are tender enough for a skewer to be poked through the middle. Start your timer as soon as you place the potatoes onto the stove and not when the water is brought to a boil.
Drain the potatoes into a colander and place into the fridge to allow for all the moisture to evaporate. Alternatively, you can pat them dry with a paper towel but it’s extremely important they are dry and there is no remaining moisture.
In a deep dish tray on a low heat, combine the butter and olive oil and cook until melted. Add the roasted garlic and a pinch of salt and pepper and cook for 2 minutes or until all ingredients are well combined. Take off the heat and toss the potatoes through the butter sauce.
Line two baking trays with baking paper and evenly distribute the potatoes across them, leaving lots of space around each potato. Using a glass or potato masher, press down onto the potatoes while still keeping them intact. Depending on your preference, you can smash them quite thin which will give you a crisper potato or smash them only slightly that will result in a fluffier inside. Both are delicious!
Drizzle the potatoes with the remaining butter sauce and bake for 40 minutes at 200 degrees celsius.
Sprinkle with some flakey sea salt and finely chopped parsley and serve immediately.