Preheat the oven to 375°F (190°C).
Place the chicken in a large bowl. Add 2 tablespoons of olive oil, the garlic and herb chicken seasoning, Italian seasoning, and smoked paprika. Toss with tongs until well coated.
Heat the remaining 1 tablespoon of olive oil and the butter in a large oven-safe braiser over medium-high heat.
Sear the chicken for 3–4 minutes per side, until browned, working in batches if needed. Transfer to a plate. The chicken will finish cooking in the oven.
Add the onion and bell peppers to the pan. Season with Tony’s More Spice Creole Seasoning to taste and cook for 3–4 minutes, stirring occasionally.
Pour in the chicken broth and stir, scraping up the browned bits.
Arrange the chicken over the vegetables and add any juices from the plate. Cover with an oven-safe lid.
Bake for about 45 minutes, until the thighs are very tender and reach at least 165°F (74°C) in the thickest part.
Carefully remove the pan from the oven and transfer the chicken to a plate. Place the pan over low heat on the stovetop.
Mix the cornstarch and cold water until smooth. Stir into the pan juices and vegetables. Cook, stirring, until thickened, bringing to a gentle simmer if needed.
Return the chicken to the pan and season with black pepper. Serve with the peppers, onions, and gravy over rice or mashed potatoes, if desired.