Preheat and prep: Set the oven to 400°F (200°C). Lightly grease a 9x13-inch baking dish. Pat the chicken dry and season both sides with salt, pepper, and smoked paprika.

Sear for better texture (optional but recommended): Heat olive oil in a skillet over medium-high. Sear chicken 2–3 minutes per side until lightly browned. You’re not cooking it through—just getting color and sealing in juices.

Sauté aromatics: In the same pan, add a touch more oil if needed and sauté red onion and bell pepper for 2–3 minutes until just softened. Add garlic for 30 seconds. Remove from heat.

Sauce the dish: Spread 1/2 cup BBQ sauce on the bottom of the baking dish. Arrange the chicken in a single layer. Spoon the onion and pepper mixture over the top.

Layer the cheese: Drizzle the remaining BBQ sauce over the chicken, then sprinkle on 1.5 cups mozzarella. Keep the last 1/2 cup for later. Add red pepper flakes if you like heat.

Bake: Cover loosely with foil and bake for 15 minutes (if using seared or cooked chicken) or 20 minutes (if using raw and unseared). Remove foil, top with remaining mozzarella, and bake 8–10 minutes more until the cheese is melted and bubbly and the chicken is cooked through.

Check doneness: The chicken should reach an internal temperature of 165°F (74°C). If using pre-cooked shredded chicken, you’re simply heating through and melting cheese.

Rest and garnish: Let it rest for 5 minutes to set the juices. Sprinkle with chopped cilantro or parsley. Add bacon crumbles or a squeeze of fresh lime if you want an extra pop.

Serve: Pair with rice, garlic bread, mashed potatoes, or a crisp coleslaw. A side of steamed green beans or roasted broccoli balances the sweetness nicely.