Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper or lightly grease it with cooking spray to prevent sticking.
Prep the chicken and potatoes: Cut the boneless, skinless chicken breasts into bite-sized cubes (about 1 to 1.5 inches). Halve the baby potatoes — if some are large, quarter them to ensure even cooking.
Season everything: In a large mixing bowl, combine the chicken and potatoes. Add olive oil, minced garlic, salt, black pepper, smoked paprika, and Italian seasoning. Toss well until everything is evenly coated.
Add Parmesan: Sprinkle the grated Parmesan cheese over the seasoned chicken and potatoes. Gently mix again to ensure the cheese sticks to the oiled surfaces and forms a flavorful coating.
Arrange on baking sheet: Spread the mixture in a single layer on the prepared sheet pan, making sure the chicken pieces and potato halves are not overcrowded. This helps them brown evenly.
Bake in the oven for 25–27 minutes, flipping the chicken and potatoes halfway through the cooking time for even browning. The chicken should reach an internal temperature of 165°F (74°C), and the potatoes should be fork-tender.
Broil for crispiness: Switch the oven to broil mode and cook for an additional 2–3 minutes to achieve a golden, crispy finish. Keep a close eye to prevent burning.
Garnish and serve: Remove the pan from the oven and sprinkle freshly chopped parsley over the top for a burst of color and freshness. Serve hot, straight from the pan, or plate individually.