In a nonstick pot, combine all ingredients except pumpkin and pistachios. Mix in 1 1/4 cups water. (Don’t worry if this seems like a lot of liquid. It will thicken up!) Bring to a boil and then reduce to a simmer. Add pumpkin and cook and stir until thick and creamy, 12 - 15 minutes. Transfer to a medium bowl and let slightly cool and thicken. Top with chopped pistachios!