For the top layer:

1. In a mixing bowl, stir together the flour and salt, then toss in the cubes of cold butter. Using your thumb and index finger, squish the pieces of butter to flatten, and continue to break it up until half is crumbly, but not completely uniform in texture; you want chickpeasize nuggets of butter.

2. Add the cold buttermilk 1tbsp at a time, blending and gathering the mixture with your hands to form a dough.

3. Shape the dough into a disk, wrap in plastic wrap and refrigerate for at least 30 minutes. While the dough is chilling, prepare the filling.

4. Add the buttermilk, sugar, vanilla, salt and flour to a blender or food processor and blend until smooth. Let the filling rest while the dough chills. Have your pie dish ready.

5. Once the dough is chilled, roll it out on a lightly floured surface or between two sheets of greaseproof paper into a 50cm round. Wrap the dough around the rolling pin to help ease it into the dish, then crimp the edges into a pattern with fingers or a fork. Place the crust in the freezer to harden for 10-15 minutes.

6. Preheat the oven to 180˚C/ gas mark 4 with a rack in the centre. Remove the unbaked crust from the freezer and bake for 12-15 minutes, or until light golden brown. Remove from the oven and pour in the filling mixture. Bake for 25-30 minutes, or until the centre is set.

7. Remove from the oven. I like to serve mine warm, but if you prefer it chilled, place it in the fridge for at least two hours or until ready to serve.

8. When it’s time to serve, add the sugar to a small saucepan and cook over medium heat until the sugar begins to brown and bubble. Swirl the pan to help any uncooked sugar liquify and cook for a few seconds, then pour out over the cold pie.

9. Working quickly, carefully tilt the pie dish to evenly distribute the browned sugar over the top. Allow to cool and harden for five minutes, and serve immediately by cracking the top and slicing. Top with berries, if desired.