Preheat your oven to 375°F (190°C). Line a rimmed baking sheet with parchment paper for easy cleanup.

Heat olive oil in a small skillet over medium heat. Add the finely chopped onion and cook until softened and translucent, about 4-5 minutes. Add the 4 cloves of minced garlic and cook for another minute until fragrant. Remove from heat and let it cool for a few minutes.

In a large mixing bowl, combine the ground chicken, Panko breadcrumbs, grated Parmesan cheese, beaten egg, the cooled onion and garlic mixture, 1/4 cup chopped parsley, dried oregano, salt, black pepper, and milk.

Gently mix all ingredients with your hands until just combined. Be careful not to overmix, as this can result in a dense and tough meatloaf.

Transfer the chicken mixture to the prepared baking sheet. Shape it into a loaf, approximately 9x5 inches.

In a small bowl, whisk together the melted butter, 2 cloves of minced garlic, 1 tbsp chopped parsley, and 1/4 tsp salt to create the glaze.

Brush half of the garlic butter glaze evenly over the top and sides of the meatloaf.

Bake in the preheated oven for 40 minutes. After 40 minutes, remove the meatloaf and brush with the remaining glaze.

Return the meatloaf to the oven and bake for an additional 10-15 minutes, or until the meatloaf is cooked through and the internal temperature reaches 165°F (74°C) when checked with an instant-read thermometer.

Let the meatloaf rest on the baking sheet for at least 10 minutes before slicing. This crucial step allows the juices to redistribute, ensuring a moist and flavorful result.

Slice and serve warm with your favorite side dishes like mashed potatoes, roasted vegetables, or a simple salad.