Butterfly the pork loin by cutting it almost all the way through parallel to the board and seasoning with salt and pepper.
Mix the herbs, lemon zest, and olive oil in a bowl.
Rub the herb mixture firmly onto the pork, roll it up tightly, and rest for 20 minutes.
Overlap pancetta slices on foil, place the pork on top, and roll into a tight sausage-shaped parcel.
Preheat the oven to 200°C.
Boil 200ml water with milk, salt, pepper, and garlic, then whisk in polenta and simmer for 45 minutes on low heat.
Sear the foil parcel in a hot roasting dish with vegetable oil for two minutes per side before roasting in the oven for 35 to 40 minutes.
Check the pork is cooked by ensuring juices run clear, then rest for five minutes.
Stir cream and parmesan into the polenta, then finish by mixing in the mascarpone off the heat.
Unwrap the pork, slice it, and serve alongside the creamy polenta.