To start, char the onions and ginger to add a hint of smokiness to the broth. Heat a dry skillet over medium-high heat and add the onions and ginger. Cook, turning occasionally, until charred. Remove from heat and set aside.

In a large pot, add the chicken thighs, charred onions and ginger, cloves, fennel, star anise, coriander, cinnamon, fish sauce, and sugar. Fill the pot with enough water to cover the chicken thighs. Bring to a boil, then reduce heat to low and let simmer for 1.5 hours.

Once the broth is done simmering, strain it to remove the solids and return the broth to the pot. Discard the solids. Shred the chicken thighs and set aside.

In a separate pot, cook the rice noodles according to the package instructions. Drain and rinse with cold water to stop the cooking process.

To serve, divide the cooked rice noodles among serving bowls. Top with the shredded chicken. Ladle the hot broth into each bowl, making sure to cover the noodles and chicken. Garnish with bean sprouts, Thai basil, coriander, lime wedges, and chilli slices for added freshness and flavour.