¾ fill pot with boiling water with 3 big pinches of salt. Bring to water to boil.
Chop potatoes into equal sizes, or if using baby potatoes you can keep them whole. Add to boiling water and par boil, about 8-12 minutes. You should be able to just stick a fork into the flesh.
Drain potatoes in a colander and leave to steam dry in the sink for 20 minutes.
Tip potatoes into roasting tray and coat with olive oil, salt and pepper. Ideally you want one flat layer of fairly snug potatoes in tray.
Roast in oven for 50 minutes, or until golden all over.
Remove tray from oven, add garlic cloves, rosemary and cinnamon. Shake tray to mix well and place back in oven for 25 minutes or until crispy to your liking.