Place chicken in a bowl and season with salt, black pepper, and white pepper. Add the egg and mix well.
Coat the chicken evenly with cornflour until lightly covered.
Heat oil and fry the chicken in batches until golden, crispy, and cooked through. Remove and drain.
In a bowl, mix soy sauce, oyster sauce, honey, brown sugar, chili flakes, chicken powder, vinegar, and water.
In a separate bowl, whisk together cornflour and water to make a slurry.
Heat a wok over high heat and melt the butter. Add garlic and sauté briefly until fragrant.
Pour in the prepared sauce mixture and stir well. Add the slurry and cook until the sauce becomes thick and glossy.
Add the fried chicken and toss quickly until evenly coated.
Drizzle with sesame oil and garnish with sesame seeds and sliced spring onions.
Serve immediately with steamed white rice.