Blanch asparagus in boiling salted water for 3 minutes, then drain and reserve 45 ml of the liquid.
Pound pork between cling film into 12x18 cm rectangles and season with salt and pepper.
Layer each pork slice with mortadella and cheese, then place two asparagus spears across the center.
Roll the pork tightly, secure with kitchen string, and coat in seasoned flour.
Fry the rolls in butter and oil over low heat for 10 minutes until golden.
Deglaze the pan with Marsala and reserved liquid, simmer for 4 minutes, and whisk in extra butter if desired.
Spoon the reduced sauce over the pork and serve immediately.