Put the lukewarm milk, lukewarm water, yeast, and honey in a large bowl. Mix well and let it sit for 5 minutes.
Add the flour, salt, and butter. Knead the dough for 10–12 minutes until smooth and elastic. Cover and let it rise for 1 hour in a warm spot, or until doubled in size.
Heat the olive oil in a frying pan over medium heat. Add the chicken pieces, cayenne pepper, black pepper, onion powder, and garlic powder. Cook for 5–6 minutes.
Meanwhile, mix the water and cornstarch in a small bowl until smooth.
Add the soy sauce, ketjap manis, sweet chili sauce, and the cornstarch mixture to the chicken. Let it simmer for 5 minutes.
Add the grated cheese and stir until melted. Mix in the spring onion. Let the filling cool completely.
Deflate the risen dough and divide into 10 equal pieces of about 65 g each. Shape into balls.
Roll one dough ball into a flat circle on a floured surface.
Place a slice of cheese and about 60 g of the chicken filling on top. Fold in half and seal the edges well.
Place the buns on a baking sheet lined with parchment paper. Let them rise for 30 minutes in a warm place.
Heat a layer of sunflower oil (about 2 cm) in a frying pan to 175 °C / 350 °F. Fry the buns on both sides until golden brown. Drain on paper towels.