Preheat oven to 400°F (200°C).
Combine ground beef, breadcrumbs, egg, milk, onion, garlic, salt, pepper, and garlic powder until just mixed.
Shape mixture into even-sized meatballs and place on a parchment-lined baking sheet.
Bake for 15–18 minutes until golden and cooked through.
In a saucepan, sauté garlic in butter until fragrant.
Add honey, soy sauce, and water; bring to a gentle simmer.
Stir in cornstarch slurry and cook until glaze thickens.
Toss baked meatballs in the sauce until fully coated and glossy.
Garnish with green onions and sesame seeds before serving.