Preheat the oven to 180°C (160°C fan-forced). Line 2 large baking trays with non-stick baking paper. Using electric beaters, cream the butter and sugar until pale and fluffy, then beat in the egg and vanilla.
Gently mix in the sifted flour and the salt. Stir in the pecans and choc chips until they are combined. Roll the mixture into balls about the size of a golf ball and place them on the prepared baking trays, about 6 cm apart to allow for spreading. Flatten them with a fork.
Bake for about 12 minutes. For a softer, chewy cookie get them out of the oven when they are just golden around the edges. For a crisper, lighter cookie, wait until they are golden all over.
Cool them on the trays for a couple of minutes until they firm up slightly, then transfer to a wire rack to cool completely. Store in an airtight container.