| 2 | whole boneless and skinless chicken breasts, about 1/2 pound (225 g) each, halved and all traces of fat removed |
| | butter-flavored cooking spray |
| | salt (optional) and freshly ground pepper to taste |
| 1 | medium Granny Smith or other tart green apple, cored and thinly sliced |
| 1 | shallot, minced |
| 1 | tablespoon (15 ml) fresh thyme leaves or 1 teaspoon (5 ml) crushed dried thyme |
| 1/4 | cup (59 ml) balsamic vinegar |
| | fresh thyme sprigs for garnish |