Preheat oven to 375°F / 190°C.
In a large bowl, combine 1 pound ground chicken, 3 minced garlic cloves, ½ teaspoon grated ginger, ¼ cup soy sauce, 1 teaspoon sesame oil, 1 teaspoon brown sugar, 1 teaspoon chicken bouillon powder, 1 teaspoon garlic powder, ½ teaspoon chili flakes, 2 chopped green onions, and ½ diced onion. Mix until well combined.
Lightly grease an 8×8 inch or 9×9 inch baking dish.
Arrange a single layer of wonton wrappers on the bottom of the dish, slightly overlapping.
Spread a thin layer of the chicken mixture evenly over the wonton wrappers.
Add another layer of wonton wrappers, then another layer of the chicken mixture. Repeat until the meat mixture is used up, finishing with a final layer of wonton wrappers on top.
Pour ½ cup hot water evenly over the entire dish.
Place this baking dish into a larger roasting dish and fill the outer dish with hot water halfway up the sides to create a water bath.
Cover tightly with foil and bake for 30 to 35 minutes until the chicken is fully cooked and the wonton layers are tender.
Remove from oven and top with sesame seeds, chopped chives, chili oil, and a drizzle of soy sauce before serving.