Preheat your oven to 300°F. Place the chicken thighs in a square 8-inch baking dish. Make a few slits in the chicken with a sharp knife.
To make the barbecue sauce, mix the tomato paste, balsamic vinegar, salt, pepper, garlic powder, smoked paprika, and sweetener in a medium bowl.
Pour the sauce over the chicken, coating it evenly. Use your hands to ensure the sauce not just covers the chicken but also gets inside the slits.
Cover the baking dish tightly with a double layer of foil and place it in the oven. It will start to smell amazing after about 2 hours, but you should cook it for 3 hours - until very tender.
Remove the pan from the oven. Carefully remove the foil - hot steam will escape - and allow the dish to cool for about 5 minutes until easier to handle.
Using a knife and fork or a rubber spatula, shred the chicken while still in the baking dish and toss it with the sauce.
Serve immediately.
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Notes
You can replace the stevia with 2 tablespoons of maple syrup; each serving of this version has about 332 calories, 22 grams of carbs, and 10 grams of sugar.How long to bake: I usually bake this dish for three hours. Baking for four hours works well to make the chicken exceptionally tender. But if you bake for so long, the barbecue sauce sometimes reduces too much despite the foil. In fact, pressed for time one afternoon, with only two hours until dinner, I baked the chicken at 400°F, covered, for 2 hours. The result was delicious and moist - so this is an option if you're in a rush.Cleanup tips: The barbecue sauce gets beautifully caramelized as the dish slowly bakes, which makes for a delicious dinner -- and a tough cleanup job later on. So, you should line the baking dish with foil. If you prefer not to use foil, allow the baking dish to cool a little (so it doesn't explode), then fill it with hot, soapy water. Let it soak overnight on a dishtowel on the counter (never put a hot Pyrex dish directly on a cold counter!). The following day, cleanup is a breeze.Storing leftovers: You can keep the leftovers in the fridge, in a sealed container, for 3-4 days. Reheat them in the microwave, covered, at 50% power. You can also freeze the leftovers for up to three months.