Preheat oven to 450ºF. In a small pan over medium heat lightly toast the nuts then cool.
In the bowl of a food processor, combine the basil, parsley, pine nuts, Boursin cheese, 1/4 cup Parmigiano-Reggiano (about a handful), some salt and pepper. Process into a smooth paste. Reserve.
Butterfly each of the chicken breasts and pound them out lightly in a plastic bag with a dash of water using a skillet or meat mallet. Season both sides of the chicken and divide the herb-cheese mixture between the four breasts, placing a scoop on one half of each breast. Fold the flap over to enclose the cheese mixture.