Heat the oil in a small frying pan on medium heat and gently cook the shallots and garlic until caramelised and golden brown (about 4-5 mins).

In a large saucepan, add the caramelised shallots and garlic, lemongrass, ginger, star anise, cinnamon stick, coriander seeds, Chinese five-spice, peppercorns, sugar, fish sauce, chicken stock and chicken breasts. Cover with a lid and bring to a very gentle simmer for about 15 mins.

Meanwhile, cook the noodles, following pack instructions, until just cooked through (do not over-cook). Rinse under cold water to prevent them sticking together. Drain and divide between serving bowls.

Strain the soup through a sieve. Discard the spices. Shred the chicken and keep to one side. Return soup to the pot and bring to a boil. Season to taste with more fish sauce if needed.

To serve, ladle piping hot soup into bowls of noodles and chicken, and top with spring onion, carrot, bean sprouts, and herbs, plus the chilli, crispy shallots and kaffir lime leaf if using. Serve with a lime wedge to squeeze over, and more fish sauce and chilli to taste.