Preheat the oven to 180°C (356°F).
In a bowl, mix the peanut butter and sugar.
Add the egg and combine well.
Add flour and baking soda, then mix into dough.
Shape the dough into balls and place them on a baking tray.
Create a pattern on top of each cookie using a fork.
Bake in the preheated oven at 180°C for 10–12 minutes.
Transfer to a cooling rack and let cool.