Preheat oven to 375°F (190°C). Line a loaf pan with parchment paper or lightly grease it.
Mix the base: In a large bowl, combine ground chicken, Parmesan, breadcrumbs, garlic, egg, milk, parsley, and seasonings. Mix just until combined — overmixing makes it tough.
Shape & bake: Press the mixture into your prepared pan and smooth the top. Bake for 35–40 minutes, or until the internal temp reaches 165°F.
Make garlic butter topping: While it bakes, melt butter in a small pan with garlic until fragrant. Stir in Parmesan and parsley.
Brush & broil: Brush the topping over the meatloaf and broil for 2–3 minutes until golden and slightly crisp.
Rest & slice: Let it rest for 5–10 minutes before slicing — this keeps all the juices inside.