Preheat the oven: Set to 425°F (220°C).
Line a baking sheet or shallow roasting pan with foil or parchment for easy cleanup. Place a wire rack on top if you want extra crispy skin.
Prep the pesto mixture: In a bowl, stir together the pesto, lemon zest, 1 tablespoon lemon juice, minced garlic (if using), olive oil, and grated parmesan. Add a pinch of red pepper flakes if you like a little heat.
Season the chicken: Pat the chicken thighs dry with paper towels.
Season both sides with salt and black pepper. Dry skin helps crisping if you’re using skin-on thighs.
Coat the chicken: Spoon the pesto mixture over the thighs, coating them well. If using skin-on thighs, lift the skin gently and rub some pesto under it for deeper flavor.
Add tomatoes (optional): Scatter cherry tomatoes around the chicken.
Drizzle them with a little olive oil and a pinch of salt.
Bake: Place the pan in the oven and bake for 25 to 35 minutes, depending on the size and type of thighs. Skin-on bone-in thighs typically need closer to 35 minutes; boneless can be done around 25 minutes.
Check doneness: Use an instant-read thermometer. The internal temperature should reach 165°F (74°C) in the thickest part, not touching bone.
Optional broil: For extra browning, broil for 1 to 3 minutes at the end.
Keep a close eye to avoid burning the pesto.
Rest and finish: Let the chicken rest for 5 minutes. Squeeze on a bit more lemon juice and sprinkle with extra parmesan. Serve with the roasted tomatoes and pan juices.