Boil sweet potatoes in their skins until tender. Peel and mash until smooth.
Add 60 ml butter and beat until smooth with an electric beater.
Stir in the condensed milk, spices, orange zest and one egg.
Roll out pastry
and line a greased pie dish.
Crimp edges with your fingertips and use extra pastry to make leaf or plate decorations around the edge of the dish.
Spoon filling into shell and bake in preheated oven for 20 minutes.
Mix together remaining
egg, syrup, sugar, 15 ml melted butter and walnuts. Remove pie from the oven after
20 minutes and sprinkle with topping.
Reduce heat to 180 ºC and bake for a further 20 minutes.
Serve warm or cold with a dollop of whipped cream.