Stir the margarine until smooth. Gradually add sugar, vanillin, salt and flavoring until it becomes a bound mass. Stir in the eggs for about 1/2 minute at the highest level.
Mix the flour, cornstarch, baking powder and cinnamon well and stir in in portions on a medium setting. Dice the banana and briefly stir in together with the hazelnuts on the highest setting.
Pour the dough into the mold and bake for about 40 minutes at 160 ° C hot air (top / bottom heat: 180 ° C).
TIP: For the decoration, mix the icing sugar with lemon juice and drizzle the cooled cake with it. Garnish with banana chips.