Preheat the oven to 350° F (180° C).
Cream together the peanut butter, butter, margarine, brown sugar and sugar until light and fluffy.
Scrape the sides of the bowl and add in the egg.
Add the flour, baking soda and salt. Mix until a very soft dough forms.
Scoop the dough into equal sized balls using approx. 1 ½ tbsp of dough for each ball.
Roll the balls of dough in sugar and use a fork to press the cookies criss cross.
Bake at 350°F (180° C) for 9-11 minutes. Pull out of the oven when they are no longer glossy on top.
Let cool on the pan. Enjoy!
