Peel the sweet potato. Cut the butternut and sweet potato in several slices. Bake them in the oven for 20-30 minutes on 350F. Let cool and remove the skin from the butternut
Grate the parsnip. Heat the coconut milk a saucepan and cook with the grated carrots for 20 minutes of low heat.
Using an electric mixed, mix the sweet potato, butternut, parsnip and coconut milk. Pour everything in a bowl and add the eggs, curry powder and flour. Combine well with a spatula. Season to taste. It should look like mashed potatoes but you can add more milk or flour if it is too liquid or too dry
Roll out the piecrust in a pan and pour in the purée.
Bake for about 20 minutes on 350F