Preheat and prep: Heat your oven to 400°F (200°C).
Lightly grease a 9x13-inch baking dish with cooking spray or oil.
Pat the chicken dry: Use paper towels to remove surface moisture. This helps the spices stick and prevents steaming.
Season the chicken: In a small bowl, mix smoked paprika, garlic powder, onion powder, chili powder, salt, and pepper. Drizzle chicken with oil, then rub the spice mix evenly over all sides.
Add the sauce: Spread a thin layer (2–3 tablespoons) of sugar-free BBQ sauce across the bottom of the dish. Nestle the chicken into the dish in a single layer.
Spoon or brush most of the remaining BBQ sauce over the tops, reserving 2–3 tablespoons.
Bake: Place in the oven and bake for 18–22 minutes for breasts (thicker pieces may need longer) or 20–25 minutes for thighs. Cook until the internal temperature reaches 165°F (74°C).
Add cheese: Remove the dish, brush the last bit of BBQ sauce over the chicken, and sprinkle generously with shredded cheese. Add red onion slices if using.
Finish baking: Return to the oven for 5–8 minutes, until the cheese is melted and bubbling. For golden spots, broil for 1–2 minutes, watching closely.
Top and rest: Let the chicken rest for 5 minutes.
Scatter crumbled bacon and fresh herbs over the top. Resting helps the juices settle and keeps the chicken tender.
Serve: Pair with a simple side like roasted broccoli, cauliflower mash, or a crisp green salad.