Pound the chilli, garlic and coriander root with a mortar and pestle, till you get a smooth paste.
Place the cooking oil in a wok over medium heat, and fry the paste until fragrant. Add in the chicken and cook till done, stirring. Season to taste with oyster sauce, fish sauce and sugar. Stir in holy basil leaves, then remove from heat.
To make topping:
Boil the durian and garlic in water until cooked, about 5 minutes. Peel the skin off the garlic; mash it with the durian. Mash in the egg yolks, salt and pepper, making sure the mixture is well-combined.
Place the chicken filling into a baking dish or divide among 4 individual ramekins/ oven-proof dishes, and top with the durian mash. Bake in a pre-heated oven at 180°C for about 15 to 20 minutes. Remove from oven, garnish with fried basil leaves and serve hot.