Add the peanut butter, egg and sugar in a mixing bowl.
Mix all the ingredients together until they have combined and the mixture is smooth.
Pinch bite-sized pieces from the dough and roll it in the palms of your hands to form balls.
Place each ball on a baking try lined with grease-proof paper. Make sure to leave enough room between each ball as they do spread a little in the oven.
Gently press each dough ball with the back of a fork and then press the dough balls again in the opposite direction so that it resembles a criss-cross pattern.
Bake in the oven for 10-13 minutes or until the outsides of the cookies are slightly crisp.
Once out of the oven leave the cookies to cool for 10 minutes before transferring to a cooling rack for a further 5 minutes.