Mix the pork mince with the fennel seeds, chilli flakes, oregano and some seasoning. Mix well with your hands until well combined, then shape into 4 burgers. Heat a drizzle of oil in a large frying pan – or fire up the BBQ and brush the burgers with a little oil – and cook the burgers for 5-7 mins on each side until cooked through.
Meanwhile, mix the tomatoes, olives, balsamic vinegar and a drizzle more oil with some seasoning to make a salsa. Top the base of each roll with 1 tbsp mascarpone, a few spinach leaves, a burger and a spoonful of the salsa, then sandwich everything with the lid.