Soak the dried cranberries in lukewarm water for 30 minutes, then dry them with blotting paper. Whip the butter with cane sugar, the seeds of the vanilla bean, salt and 1 egg. Mix with care.
Add the flour (previously sieved) as well as the baking soda, milk and cranberries; stir with a spatula. Add at this point the peanut butter and keep on stirring.
Cover 2 baking trays with some parchment paper and use an ice cream spoon to place many little balls of the prepared dough on the tray (they have to be of 4 cm in diameter and well distanced). Bake the biscuits in a pre-heated oven at 180° for 20 minutes. Let them cool down before serving.