Line a baking sheet with baking parchment.
Place the pecans in a skillet or frying pan over a medium heat. Cook for a couple of minutes, stirring often, until they smell toasty and have started to brown slightly.
Remove from the heat and allow to cool then chop them very finely, either with a sharp knife or in a food processor. Aim for pieces about the size of a grain of rice.
Cream together the butter, sugar, vanilla extract and salt for a couple of minutes until smooth and creamy.
Add the flour and cinnamon and stir until no lumps of butter remain.
Add the pecans and stir until they are well distributed. The mixture should be clumping together into a dough.
Scoop up tablespoon amounts of dough and use your hands to roll them into balls. Place them slightly spaced apart the lined baking sheet.
Pop the baking sheet in the freezer for 15 minutes, or the fridge for 30, while you preheat the oven to 180°C/160°C fan/350°F/gas mark 4.
Bake the cookies for 15-18 minutes (mine take 18) until they are lightly browned on the underside, they will still be fairly pale on top.
Sift some icing sugar into a shallow bowl. Leave the cookies to cool on the tray for 5 minutes then roll them in the icing sugar to coat and place on a wire rack to cool completely.
Once the cookies are completely cold roll them in icing sugar again and store in an airtight container.