Heat oven to 180C/160C fan/gas 4 and line 2 large baking trays with baking parchment. Measure the peanut butter and sugar into a bowl. Add ¼ tsp fine table salt and mix well with a wooden spoon. Add the egg and mix again until the mixture forms a dough
Break off cherry tomato sized chunks of dough and place, well spaced apart, on the baking trays. Press the cookies down with the back of a spoon.
Sprinkle and lightly press some peanut nibs onto the top of the cookies.
Bake for 12 mins, until golden around the edges and paler in the centre. Cool on the trays for 10 mins, then transfer to a wire rack and cool completely. Store in a cookie jar for up to 3 days.