Preheat the oven to 375 degrees F. Place the chicken in a non-stick or parchment paper-lined baking dish. Brush the skin with 1 Tbsp. of the oil; season with salt and pepper. Roast the chicken for 35 to 40 minutes, or until cooked through.
When the chicken is 20 or so minutes from being done, place the remaining oil in a wide pot or skillet set over medium to medium-high heat. Add the eggplant, onion, bell pepper, zucchini, mushrooms and garlic and cook until the mushrooms are tender and any moisture has evaporated. Add the remaining ingredients, except basil, bring to a simmer, and simmer 10 minutes, until vegetables are quite tender. Stir in the basil; season with salt and pepper. When cooked, plate the chicken and serve with ratatouille.
Note: In this recipe, diced means to cut in 1/2" cubes.