Pat and season the chicken: Pat the thighs dry with paper towels. Season both sides with 1 teaspoon salt and 1/2 teaspoon black pepper. Dry skin helps you get a better sear.

Sear the chicken: Heat the olive oil in a large skillet or Dutch oven over medium-high. Place the chicken skin-side down and cook until the skin is golden and crisp, about 6–8 minutes. Flip and sear the second side for 3–4 minutes. Transfer chicken to a plate; it will finish cooking in the sauce.

Cook the aromatics: Reduce heat to medium. Spoon off excess fat if needed, leaving about 2 tablespoons in the pan. Add the onion and a pinch of salt. Cook, stirring, until softened and lightly golden, 4–5 minutes. Add the garlic and cook 30 seconds until fragrant.

Build the tomato base: Stir in the tomato paste and cook 1 minute to caramelize it slightly. Add crushed tomatoes, chicken broth, oregano, basil, and red pepper flakes if using. Stir to combine and bring to a gentle simmer.

Simmer with the chicken: Nestle the chicken and any juices back into the skillet, skin-side up. Reduce heat to medium-low, cover loosely, and simmer 15–20 minutes, until chicken is cooked through. For bone-in thighs, aim for an internal temperature of 175°F for best tenderness.

Finish the sauce: Stir in the heavy cream and butter. Let the sauce simmer uncovered 3–5 minutes to thicken slightly. If using Parmesan, add it now and stir until melted and smooth. Taste and adjust salt and pepper.

Garnish and serve: Sprinkle with chopped parsley or basil. Serve hot over pasta, polenta, rice, mashed potatoes, or with warm bread for dipping.