Preheat the oven to 350°F (180°C).
Spread the pecans onto a baking tray and bake for 10-12 minutes, or until toasted and fragrant. Roughly chop nuts and set aside.
Roll out the pie crust and line a 9-inch (23cm) pie tin with it. Place in the fridge until needed.
In a large bowl, whisk the eggs, granulated sugar, brown sugar and softened butter.
Next whisk in the buttermilk, vanilla and salt until the ingredients have combined.
Whisk in the flour until the filling is smooth and lump free.
Lastly, fold in the chopped pecans.
Pour the filling into the crust and place the pie in the oven.
Bake for about 1 hour 20 minutes, or until just set.
Let cool for several hours before cutting.
Serve pie at room temperature with a scoop of vanilla bean ice cream. Store leftovers, loosely covered, in the refrigerator for up to 4 days.