To the same pan, add oil.
When hot, add red curry paste. Stir fry for about 3 minutes.
Add chicken. Toss to coat chicken with the curry paste.
Add water and coconut milk. Stir.
Bring to a boil. Simmer for about 5-6 minutes or until chicken is cooked through.
Add fish sauce, palm sugar, and pumpkin. Stir to combine.
Bring to a boil. Simmer for about 4-5 minutes or until pumpkin is tender.
Add basil leaves, if using, and heat through.