Place in a pan, cover with water and turn on the heat.
Bring to the boil then turn down the heat and cook for around 15 minutes until soft enough to gently pierce with a fork.
Drain the sweet potatoes and place in a food processor.
Whizz until completely smooth - you may need to mix it around a few times.
Place the puréed sweet potatoes in a pan with all the other ingredients for the filling (you can use the same pan as the one you used to cook the sweet potatoes).
Stir well, ensuring the cornflour (cornstarch) has dissolved completely.
Once the mixture is mixed well, cook on a medium heat, stirring continuously until thickened and gently bubbling.
Depending on the consistency and texture of your sweet potato purée, it may not properly mix into your milk - if this is the case you can transfer the mixture back into the food processor to blend until completely smooth.
Leave to cool slightly before pouring into the pastry.
For the pastry:
Preheat the oven to 180 degrees Celsius (350 degrees Fahrenheit).
Combine all ingredients in a large bowl along with about 7 tablespoons of water, until it forms a firm dough - add the water a few tablespoons at a time so that you don’t add too much!
You can keep this pastry dough in the fridge for up to a day if you like, but there is no need to chill it before using.
Place the pastry dough into a greased pie dish and use your fingers to carefully press it across the bottom and up the sides of the dish (I used a 9inch/22.5cm pie dish).
You can use a fork or your fingers to create a pretty pattern around the edge if you like.
Pour the filling into the pie crust just before putting in the oven (as otherwise the dough might 'melt').
Bake in the oven for around 40 minutes, until the pastry crust is firm to the touch and golden brown.
Leave to cool completely before cutting, ideally putting the pie in the fridge for a couple of hours, to allow the filling to set properly.
Keeps covered in the fridge for up to a few days.
Video
Notes
*I used regular orange sweet potatoes for this Sweet Potato Pie, but you can also use white sweet potatoes or purple sweet potatoes. However, both white and purple sweet potatoes have a starchier texture than orange sweet potatoes, so if you use either of these then the texture of the pie filling will be denser.**You can alternatively use almond flour.