Soak the cedar plank in water for at least 4 hours to ensure it smokes well and doesn’t catch fire during the cooking process!
Slice the top off the bulb of garlic and double wrap in tin foil before chucking it in Roccbox for 15 minutes. Set to one side.
Mix together the pil pil ingredients and sprinkle 3 Tbsp of it over the prawns. Toss together and lay the prawns on the plank.
Turn the flame down to its lowest setting and pop the plank in the front third of the oven (I like to use a pair of tongs and a pallet knife here to help me move and turn the plank).
Cook the prawns for 2 minutes, rotate the plank and cook for another 2 minutes.
Squeeze the roasted garlic into a serving bowl and add half the oil – breaking the garlic up with a fork as you do so.
Add the hot prawns, the remaining oil and sprinkle over the parsley.