Place chicken pieces, skin side up, in a slow cooker.

Season with salt and pepper.

Add 2 cups of chicken stock.

Cook on high for 4 hours.

Remove the chicken and reserve the stock.

Strain the stock using a fat separator to remove solids and fat.

Pour the strained stock into a soup pot.

Remove the skin from the chicken and discard.

Shred the chicken with forks.

Add the shredded chicken to the stock in the pot.

Bring the stock to medium heat.

Slice the mushrooms in half vertically.

Add mushrooms, coconut milk, remaining 2 cups of chicken stock, Thai chilies, lemongrass, and galangal to the pot.

Stir well and bring to a simmer.

Lower the heat and simmer for 45 minutes.

Add lime juice, kaffir lime leaves, and fish sauce.

Stir and cook for another 5 minutes.

Serve over cooked jasmine rice.

Garnish with Thai basil or cilantro.

Inform guests to avoid eating the lemongrass, kaffir lime leaves, and galangal.