Add the diced tomatoes, coconut milk and chicken stock. Turn up the heat and bring the pan to a simmer: don’t boil as this will separate out the coconut milk.
Season to taste with salt and, if using, red pepper flakes. Stir in either the pumpkin puree OR sweet potato puree to thicken. Bring back to a simmer.
Add the chicken and summer squash noodles. Cook until the chicken is heated all the way through and the noodles have softened, about 5 minutes.
Before serving, stir in the fresh spinach and let it wilt slightly.