Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Dice the eggplant, zucchini, and red bell pepper into uniform 1-inch cubes.
Place the diced vegetables on the baking sheet and toss with 0.5 tablespoon of olive oil, 1 teaspoon of Herbes de Provence, and half of the salt and pepper.
Season the chicken breast with the remaining olive oil, Herbes de Provence, salt, and pepper, then place it on the baking sheet with the vegetables.
Roast in the oven for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and slightly caramelized.
While the chicken roasts, finely dice the onion and mince the garlic.
In a small saucepan over medium heat, sauté the onion and garlic until soft and translucent, about 5 minutes.
Stir in the tomato puree and simmer on low heat for 10 minutes to allow the flavors to meld.
Once roasted, slice the chicken into strips and toss the roasted vegetables into the warm tomato sauce.
Plate the vegetable ratatouille and top with the sliced chicken breast to serve.