Step 1: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper.
Step 2: Pat the chicken breasts dry with paper towels. Slice each chicken breast horizontally to create thinner cutlets, or pound them to an even 3/4-inch thickness for quicker, even cooking.
Step 3: In a large bowl, toss the chicken with 1 tablespoon of olive oil, 1 tablespoon of minced garlic, 1 teaspoon of dried Italian seasoning, 1/2 teaspoon of salt, and 1/4 teaspoon of black pepper. Ensure the chicken is well coated.
Step 4: In the same bowl (no need to wash it!), toss the sliced zucchini with the remaining 1 tablespoon of olive oil, remaining 0.5 tablespoon of minced garlic, remaining 0.5 teaspoon of dried Italian seasoning, remaining 1/2 teaspoon of salt, and remaining 1/4 teaspoon of black pepper.
Step 5: Arrange the seasoned chicken and zucchini in a single layer on the prepared baking sheet. Make sure there is some space between the pieces to allow for even roasting and browning.
Step 6: Roast for 20-25 minutes, or until the chicken is cooked through (internal temperature reaches 165°F/74°C) and the zucchini is tender-crisp and slightly caramelized. For more even browning, you can flip the chicken and stir the zucchini halfway through the cooking time.
Step 7: Remove the baking sheet from the oven. Garnish with fresh chopped parsley, if desired, and serve immediately. This dish is fantastic on its own or served with a simple grain.