Melt the butter in a pan and sweat the shallots with a good bit of seasoning until soft. Blitz up all the remaining stuffing ingredients except the truffle oil and add to the pan. Cook out for 2-3 minutes before seasoning the mix and adding the truffle oil. Set to one side to cool.
Lay the butterflied pork fillet on a board, season and add the stuffing (you may not need all of it depending on the size of your pork!) leaving a 1cm ‘frame’ around the outside.
Roll the pork up around the stuffing carefully and set to one side.
Lay out the pancetta rashers on a board and place the stuff pork on top before rolling the pancetta around the pork and tying securely with butchers string. Rub the stuff meat all over with a lug of olive oil and transfer to a cast iron tray and cover with foil.
Turn the pre heated Roccbox to its lowest setting and pop the tray straight in. Cook in 10 minutes, rotating halfway through the cook time.
Next, remove the foil and return the pan to Roccbox, still on low flame, for another 5-6 minutes making sure to rotate and turn the pork at regular intervals to crisp up the pancetta. Transfer to a plate and cover loosely with foil to rest for 10 minutes.
Add the sprouts to the pan with smashed cloves of garlic and return to Roccbox for 5-6 minutes, shaking regularly, until the sprouts are cooked. Season and transfer to a serving bowl, pour over the pork resting juices, carve the pork and serve.