Preheat oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Slice the zucchini and yellow squash into half-moons, and halve the cherry tomatoes.
Cut the chicken breast into bite-sized cubes to ensure even cooking and quick roasting.
In a large bowl, whisk together the olive oil, minced garlic, dried oregano, sea salt, and black pepper.
Add the chicken and vegetables to the bowl, tossing thoroughly to coat every piece in the herb oil.
Spread the mixture in a single layer on the prepared baking sheet, ensuring no overcrowding.
Roast for 18-22 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
Garnish with fresh chopped parsley before serving warm.