Preheat the oven to 400°F (200°C). Line a large baking sheet with parchment paper or lightly grease it.
In a mixing bowl, combine 3 tablespoons of olive oil, minced garlic, Italian seasoning, salt, and black pepper.
Add the halved baby potatoes to the mixing bowl and toss until they are well-coated with the mixture.
Place the seasoned potatoes on one side of the baking sheet in a single layer.
Coat the chicken breasts with the remaining 1 tablespoon of olive oil and sprinkle them with half of the grated Parmesan cheese.
Place the chicken breasts on the baking sheet alongside the potatoes.
Bake in the preheated oven for 25 minutes. After 25 minutes, remove the baking sheet from the oven, sprinkle the remaining Parmesan cheese over the chicken and potatoes, and return to the oven.
Continue baking for an additional 15 minutes, or until the chicken reaches an internal temperature of 165°F (75°C) and the potatoes are golden and crispy.
Remove from the oven and let it rest for 5 minutes. Garnish with chopped parsley before serving.