Mix chicken wings, salt, pepper and oil in a bowl. Arrange wings on a greased baking rack so that they are not touching each other. Roast in the oven for 35-40 minutes, turning them over halfway through cooking until they are golden and done.
Heat oil in a small saucepan on medium-low heat. Add ginger, garlic and chilli. Sauté for a few seconds until fragrant. Reduce heat to low. Add 5-spice powder, marmalade, vinegar, soy sauce and orange juice. Simmer for a few minutes. Add stock mixed with cornflour. Simmer for a few minutes until sauce is thick and fragrant.
Add roasted chicken wings to a large bowl. Add half of the sauce and mix well.
Place sticky chicken wings on a serving platter. Top with sesame seeds and spring onion. Serve with extra sticky marmalade sauce on the side.