In a large bowl, combine water, milk, honey, and instant yeast; let it activate for 5 minutes.
Add egg, sunflower oil, flour, salt, and butter; knead until a smooth dough forms.
Cover and let the dough rise for 1 hour or until doubled in size.
Meanwhile, prepare the chicken mixture by finely dicing or mincing chicken filet.
Mix chicken with salt, onion powder, garlic powder, cayenne powder, black pepper powder, sambal oelek, soy sauce, and egg.
In a separate bowl, combine cornstarch, salt, black pepper powder, and onion powder; coat the chicken mixture evenly.
Form the chicken into small portions for the buns.
Once the dough has risen, punch it down and divide into 14 equal pieces.
Flatten each dough piece and place a portion of chicken mixture inside; seal to form buns.
Place buns seam side down on a baking tray lined with parchment paper.
Prepare the topping by mixing Parmesan cheese, cayenne powder, onion powder, and black pepper powder.
Brush the buns lightly with milk and sprinkle the cheesy topping over them.
Preheat oven to 180°C (350°F).
Bake the buns for 20-30 minutes until golden brown and cooked through.
While baking, prepare the sauce by combining mayonnaise, chili sauce, and sambal oelek in a bowl.
Serve the buns warm with the spicy sauce on the side for dipping.
