Preheat oven to 160°C fan (180°C no-fan).
Mix together the butter and peanut butter until smooth. Add the sugars and cream until fluffy.
Add the eggs, one at a time, and beat until well blended, then add the vanilla.
Sift together the dry ingredients, and stir into the wet until well mixed.
Shape the dough into balls about 40-50g each, and place on a parchment lined tray. Flatten slightly and bake for 10 minutes, turning the tray halfway.
Allow to cool on wire racks, then dip in chocolate (optional) and sprinkle with chopped peanuts.