Prepare and keep warm in a 200°F oven:
Wipe out the skillet, place over medium heat, and add:
Add and cook, stirring, until rendered and browned:
Transfer to a small bowl and set aside. Pour off all but 1 tablespoon of fat from the skillet and add:
Cook, stirring, until softened, about 5 minutes. Increase the heat to medium-high and add:
Cook, until softened, 3 to 5 minutes. Return the cooked pancetta to the skillet, along with:
Bring to a boil and cook until the mixture has reduced to one-quarter of its original volume, about 5 minutes. Add:
Boil until the sauce is thick enough to lightly coat a spoon, about 5 minutes. Remove the thyme sprigs and stir in:
Spoon the sauce over the chicken and serve immediately.