Add 2 tablespoons of the coconut milk to a large pot or deep pan over medium-high heat. Add the onion and garlic and sauté for 3 minutes, stirring frequently and keeping an eye on the heat to prevent burning.
Add another tablespoon of coconut milk along with the galangal, lemongrass, chilli and coriander root. Cook for 5 minutes, stirring regularly and reducing the heat if needed.
Add the lime zest and fish sauce and stir well to deglaze the bottom of the pot, as well as salt and pepper to taste.
Add another few tablespoons of coconut milk and continue stirring until everything is fragrant and well combined.
Place rice noodles in a separate bowl and cover with warm water to soak for 10 minutes - not boiled water!
Back to the main pot…Slowly pour in the chicken stock and add the brown sugar. Stir well and bring the mixture to a simmer to slightly reduce.
Add the remaining coconut milk and simmer for another few minutes.
Add the cooked chicken and greens, until warmed through and wilted.
Serve over cooked rice noodles and top with fresh chilli and coriander, and enjoy!