Preheat oven to 425°F.
Season chicken all over with salt and pepper.
In a large oven-ready skillet, heat oil over medium-high heat.
Place chicken, skin side down, in the hot skillet. Cook until golden brown, about 8 to 10 minutes. (Shift the chicken around in the skillet occasionally to prevent sticking).
Remove from heat and turn chicken over. Place skillet in the oven for 20 minutes until chicken is completely cooked (internal temperature of 165°F). Use tongs to remove chicken onto a platter or plate.
Discard the oil and any rendered grease from the skillet. Leave the brown bits that have stuck on the surface of the pan.
Meanwhile, bring a pot of salted water to a boil. Add the pasta and cook until al dente, typically about 10 to 12 minutes, check package instructions for guidance. Add the broccoli in the final 3 minutes of cooking. Drain, and set aside.
Return the skillet to the stove over medium heat and add the butter. Once melted, stir in the flour and whisk for about 2 minutes.
Stir in the milk, cream, chicken stock, Dijon, Worcestershire sauce, garlic powder, 1 tsp salt, and ¼ tsp ground black pepper. Stir constantly until thickened, about 5 minutes.
Add the cooked pasta and broccoli and gently stir until well-mixed. Stir in the cheese, and then nestle the cooked chicken thighs in the skillet. Serve at once.