Preheat the oven on 180℃ (356℉).
Mix all the ingredients up until the salt to a bowl, whisk to combine, then add the remainder of the ingredients except the blueberries and cornstarch, mix to combine very well, set aside and in a separate bowl, add the cornstarch and the blueberries, toss to cover the blueberries with the cornstarch, add them to the cake batter, then fold the batter delicately.
Transfer the batter to a greased mold (mine is 25cmX13cmX6cm), add a few extra blueberries on top of the cake, then put it in the oven for one hour. Remove the cake from the oven, wait until it cools down completely then drizzle the lemon icing to the top and finish garnishing with fresh blueberries and lemon zest.
TIP: If you don't have powdered sugar, add regular sugar to a blender and blend until it becomes a fine powder.