Preheat oven to 425°F and line a large sheet pan with parchment paper.
Coat chicken breasts generously with pesto on both sides and place in the center of the sheet pan.
In a bowl, toss potatoes, green beans, cherry tomatoes, olive oil, garlic, Italian seasoning, salt, and pepper until evenly coated.
Arrange vegetables around the chicken in a single layer, making sure potatoes have space to crisp up.
Roast for 20-22 minutes until chicken reaches 165°F internally and vegetables are tender.
Sprinkle mozzarella cheese over chicken and return to oven for 2-3 minutes until melted. Garnish with fresh basil and serve immediately.