Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Toss the cubed eggplant, sliced zucchini, and chopped bell peppers with half of the olive oil, sea salt, and black pepper on the baking sheet.
Roast the vegetables for 20 minutes, flipping halfway through, until they are tender and slightly caramelized.
While the vegetables roast, season the chicken breast with salt and pepper and sear it in a large skillet with the remaining oil over medium-high heat until golden and cooked through.
Remove the chicken from the skillet to rest, then in the same pan, sauté the diced onion and minced garlic until soft and fragrant.
Stir in the tomato puree and herbes de Provence, then fold in the roasted vegetables and simmer for 5 minutes to allow the flavors to meld.
Slice the chicken into strips and serve it over a generous portion of the aromatic ratatouille, finishing with a sprinkle of fresh basil.