Preheat your oven to 180°C. In a bowl, cream the softened butter (just take it out of the fridge in the morning before you bake) and the sugars together.
Add the egg and spice, and beat until it has the consistency of a heavy mousse, then gently fold in the flour and baking soda. When a smooth and thick dough forms, add the chocolate chunks. Pick off pieces of dough and roll into walnut-sized balls. Place them on a parchment-lined baking sheet.
Flatten each ball slightly by gently pressing down with the palm of your hand.
Bake for 10 minutes – make sure you don’t overcook them.