Spinach-Parmesan stuffing provides great flavor in boneless, skinless chicken thighs. Try it with the optional chicken livers in the stuffing for an extra-rich treat. And don't worry, even though when stuffed it looks like the filling will ooze out, it doesn't. The egg in the stuffing acts as a binder to keep everything in place. The recipe makes plenty of sauce, so be sure to cook up some pasta or make mashed potatoes to serve alongside the saucy chicken.