Grease a large baking tray, or preferably use a silicone treated paper or a mat
Cream the butter and the sugar very well. The b utter must become light and fluffy and the sugar dissolved.
Add the vanilla and salt.
Finally add the pecans and the flour, mixing very thoroughly.
Using your hands shape spoonfuls of the dough into walnut sized pieces.
Arrange on the baking tray.
Bake for 30 minutes. They must be pale and crisp.
Place the icing sugar in a large plastic bag. As the hot biscuits come out of the oven toss them into the plastic bag and gently shake to coat the biscuits. I empty them onto the used baking tray and sift some additional icing sugar over them. Leave the biscuits to cool completely.