Cook the conchiglioni in boiling salted water until just al dente, drain.
Heat the oil in a frying pan. Salt the chicken, brown the meat for approx. 6 mins. on each side. Remove, pull away the meat in a bowl using two forks, set aside. Add a dash of oil to the same pan, briefly sauté the onion and garlic. Add the peas, cook for approx. 3 mins., season. Mix the cream cheese with half of the peas, stuff the conchiglioni with the mixture. Add the remainder of the peas to the chicken along with the balsamic, mix.
Plate up the conchiglioni, top with the peas and chicken.