Organic vegan shortbread with banana and chocolate from La Sablésienne — the sweetest of the four, and sold in the small pack rather than the 110 g carton, which makes it the one to try first.
A useful thing about the small format. Banana is a divisive flavour in baking in a way vanilla and chocolate are not — people who love it really love it, and people who associate it with artificial banana sweets never quite get past that. A small pack costs a fraction of a full carton and answers the question. If it turns out to be your thing, buy the big one next time.
Why banana bread tastes of banana and a fresh banana barely does. The aroma comes from esters, principally isoamyl acetate, which develop as the fruit ripens and its starch converts to sugar. A green banana contains almost none; a black, unlovely one at the bottom of the fruit bowl is full of them. That is why every good banana recipe insists on over-ripe fruit, and why so much banana confectionery smells more of banana than the actual fruit does — isoamyl acetate on its own is the archetypal “banana sweet” smell.
Banana and chocolate is one of the more reliable pairings in baking: banana's esters sit high and bright, cocoa sits low and bitter, and they occupy almost no common ground, so neither competes with the other.
Still a sablé — short, dry and sandy rather than soft, made by rubbing fat into the flour before any liquid so that gluten cannot develop. And still vegan, which for a biscuit built traditionally on butter and egg yolk is a real technical feat.
Organic and vegan. Check the pack for allergens — the range is produced alongside a sesame biscuit. Available at Só Verde, an organic concept store in Foz, Porto.