Preheat your oven to 375°F (190°C). Lightly grease a loaf pan, or place a piece of parchment paper inside for easy removal. Have all your ingredients ready.

In a small skillet, heat a tablespoon of olive oil over medium heat. Add the finely diced onion and cook until softened and translucent, about 5-7 minutes. Then, stir in the minced garlic and cook for another minute until fragrant. Let it cool slightly.

In a large mixing bowl, gently combine the ground chicken, cooled onion and garlic mixture, ½ cup of the grated Parmesan cheese, breadcrumbs or panko, eggs, milk, fresh parsley, half of your marinara sauce (½ cup), Italian seasoning, salt, pepper, Worcestershire sauce (if using), and Dijon mustard (if using).

The key to a juicy chicken meatloaf is not to overmix! Use your hands to gently combine everything without compacting the meat too much. If adding ricotta or sun-dried tomatoes, fold them in now gently.

Transfer the mixture into your prepared loaf pan. Gently press it down to form an even loaf. If you're adding mozzarella, create a small trench down the middle of the loaf, fill it with shredded mozzarella, and then gently cover it with more chicken mixture.

In a small bowl, mix the remaining ½ cup of marinara sauce with a tablespoon or two of remaining Parmesan cheese. This will be your simple, yet incredibly flavorful chicken meatloaf glaze.

Spread the marinara-Parmesan glaze evenly over the top of the meatloaf. Place the loaf pan in the preheated oven. Bake for 50-60 minutes, or until the internal temperature reaches 165°F (74°C) with an instant-read thermometer. The top should be beautifully golden and bubbly.

Once baked, remove the meatloaf from the oven and let it rest in the pan for at least 10 minutes before slicing. This resting period is crucial, allowing the juices to redistribute, ensuring a truly moist chicken meatloaf.