Preheat the oven to 325 and put some icing sugar in a shallow dish to have ready.  Using your electric mixer, beat together the butter and 1/3 cup of icing sugar until the mixture is fluffy, then add in the vanilla and beat again.  Add the pecans and flour and beat again until everything is well combined – the dough will be quite stiff.

Roll the dough into bite-sized balls (I like 15 grams for size) and place on a baking sheet covered in parchment.  If your kitchen is super warm, consider refrigerating the balls for a half hour or so prior to baking.  Arrange on the baking sheet – a full sheet works as they spread very little!, then bake for 18 to 20 minutes until the bottoms just start to brown.  Leave them to cool for a few minutes on the baking sheet, then roll them carefully in the extra icing sugar while they are still warm and set them on a rack to cool completely.  Eating only one won’t be an option!