Prep the oven and pan. Preheat the oven to 400°F (205°C). Line a baking sheet with foil and set a wire rack on top if you have one. The rack helps the chicken cook evenly. If you don’t have a rack, lightly oil the foil.

Pound to even thickness. Place chicken breasts between two pieces of parchment and gently pound the thick end so each piece is about 3/4–1 inch thick. This helps them cook at the same rate.

Mix the spice rub. In a small bowl, combine smoked paprika, garlic powder, onion powder, chili powder (if using), salt, and pepper.

Season the chicken. Pat the chicken dry with paper towels. Rub with olive oil, then sprinkle the spice mix on both sides, pressing it in lightly.

Optional quick sear for color. Heat a large oven-safe skillet over medium-high with a thin film of oil. Sear chicken 1–2 minutes per side until lightly browned. Transfer to the prepared rack or keep in the skillet if it’s oven-safe.

Make the sauce blend. Stir the BBQ sauce with brown sugar, apple cider vinegar, and butter (if using). The sugar helps caramelize; vinegar keeps it bright; butter adds gloss.

First sauce layer. Brush about half the BBQ sauce over the tops and sides of the chicken. Keep the rest for later.

Roast. Bake for 10–12 minutes, then remove and brush on more sauce. Return to the oven for another 5–10 minutes, until the thickest part reaches 165°F (74°C) on an instant-read thermometer.

Broil for caramelization (optional). For extra char, set the oven to broil and cook 1–2 minutes, watching closely so the sauce doesn’t burn.

Rest and serve. Let the chicken rest 5 minutes. Brush with any remaining warm sauce. Slice against the grain and garnish with chopped parsley or chives. Serve immediately.