Boil sweet potatoes in skin for 55 minutes (or until very soft throughout).
Remove sweet potatoes and wash in cold water. Peel skin and dice.
Use electric mixer to blend sweet potatoes on high, until there are no bumps, lumps or strings.
Add butter, milk and eggs gradually.
Add cinnamon, nutmeg and vanilla essence and beat on medium until smooth.
Meanwhile, grease a pie tin (20-25cm). Coat generously with pastry sheets, and fold over the edges. Put aside excess pastry.
Pour prepared mixture into tin. Excess pastry can be used to create a lattice effect on top of mixture.
Bake at 175 degrees celcius for 50-60 minutes (until inserted skewer comes out clean).
Allow to cool in tin.
To serve: top with vanilla ice-cream or whipped cream.
2 medium Spencer Ranch sweet potatoes
1/2 cup butter, softened
1/2 cup full cream milk
1/2 cup white sugar
1/4 cup brown sugar
1 teaspoon cinnamon
1 teaspoon nutmeg
1/2 teaspoon vanilla essence
2 frozen shortcrust pastry (MYO if you prefer)
Vanilla ice-cream, to serve