Preheat the oven to 425° F and line a rimmed baking sheet with parchment paper. Next, grab a big bowl and cutting board. Chop all the vegetables (bell peppers, summer squash, zucchini, onion, and eggplant) into 2-inch pieces. Toss the vegetables and chickpeas with olive oil and salt then evenly layer the mixture across the sheet pan. Place the chicken thighs on top of the chickpea ratatouille mix. Sprinkle chicken with salt and pepper.
Roast the sheet pan dinner for 45 minutes. After 25 minutes, toss in the tomatoes. If you’d like, turn the broiler on for the last few minutes to brown the chicken skin. Serve with a bowl of basil pesto for drizzling over everything.