Coat a large skillet lightly with olive oil and set it over medium-high heat.
Add the pancetta and cook until just crisp and lightly browned.
Remove with a slotted spoon, leaving the fat in the pan, and set aside.
Put the flour on a plate.
Pat the cutlets dry. Season them on both sides lightly with salt and amply with pepper.
Heat the skillet with the pancetta fat over medium high.
Add more olive oil, if needed, to get about 2 Tbs. fat in the pan.
When the fat is hot, dredge a cutlet through the flour on both sides.
Shake off the excess flour and immediately put the cutlet in the pan. Do the same with as many cutlets as will fit in the pan without touching.
Sauté the cutlets, turning once, until browned on both sides; if thin, they should cook through in just a few minutes total. Transfer the cooked cutlets to a plate and continue sautéing the rest, adding more oil if necessary.
Transfer these to the plate as well.
Pour off the excess fat.
With the pan over medium-high heat, add the Marsala and scrape up any browned bits from the bottom of the pan.
Cook until the Marsala is reduced by about a quarter.
Stir in the cream and boil until you get a nicely thickened sauce. Return the chicken and pancetta to the pan and turn the cutlets over to coat.
Let them reheat for 30 seconds to 1 minute. Serve with the sauce and a sprinkling of parsley, if you like.