Transfer to a large saucepan of water and bring to a gentle boil. Par-boil potatoes for 10-15 mins, until you can easily pierce with a fork. Then drain and add back to saucepan. Give the saucepan a good shake to fluff up the potatoes, you want to aim for very fluffy but careful not to mash your potatoes! Lay potatoes out onto a cooling rack and allow to cool completely. You can potatoes leave to cool overnight.

Preheat oven to 180°C/ 365°F. Add enough olive oil to coat bottom of roasting tin, then place on stove on low-medium heat. Add potatoes to roasting tin and flip until potatoes are coated all over with olive oil. Chuck in garlic cloves (whole) and rosemary, then place in oven. Roast for 40 mins- 1 hour 20 mins, flipping every 20 mins. Once they are beautiful and golden and crispy all over, remove form oven.

For garlic butter, melt butter in a small pan on medium heat, then add garlic and sauté for 2-3 mins, until garlic turn golden and crispy. Add to roast potatoes before serving, along with grated parmesan and dried parsley