Beat the egg and egg yolk with the brown sugar, salt and vanilla-infused sugar until frothy. Squash the banana, work in the oil and then fold in the rest of the ingredients.
Form rolls around 4 cm thick from the homogeneous dough, roll in clingfilm and freeze for at least 12 hours.
Before baking, cut the cookies into 2 cm thick slices and arrange on a baking tray lines with baking paper. Bake at 180°C for approx. 12-14 minutes.