Preheat your oven to 375°F (190°C) and line a small loaf pan or baking sheet with parchment paper for easy cleanup.
In a large mixing bowl, combine the ground chicken, egg, almond flour, finely diced yellow onion, minced garlic, chopped fresh parsley, dried oregano, sea salt, and black pepper.
Gently mix the ingredients using your hands or a spatula until just combined, ensuring you do not overwork the meat to maintain a light texture.
Transfer the chicken mixture to the prepared pan and shape it into a uniform loaf approximately 2 inches thick.
In a small bowl, whisk together the tomato paste and balsamic vinegar until the glaze is smooth and well incorporated.
Brush the balsamic glaze evenly over the entire top surface of the meatloaf.
Bake in the center of the oven for 25 to 30 minutes, or until the internal temperature reaches 165°F (74°C) on a meat thermometer.
Remove from the oven and let the meatloaf rest for at least 5 minutes before slicing to ensure it stays juicy.