Method

• 1.
  Preheat oven to 200°C/180°C fan-forced. Lightly grease an 11cm x 21cm (base) loaf pan and line with baking paper, with 2cm paper overhanging on each side.
• 2.
  In a stand mixer fitted with the paddle attachment, beat sugar and butter on medium speed for 2 minutes, or until pale. Add the eggs, one at a time, beating well after each addition, until combined. Add the banana, yoghurt and vanilla and stir until fully combined. Sift over the flour, baking powder and bicarb and stir until just combined.
• 3.
  Measure 1 cup of batter and place in a medium bowl with the cinnamon. Stir until combined. Spoon one-third of the remaining plain batter into prepared pan. Level surface with a spatula, then create a slight divot along the centre. Dollop half the cinnamon batter into divot and spread with a spatula, being careful not to mix through the plain batter (this will give you a distinct cinnamon swirl). Repeat with a layer of plain batter and cinnamon batter, then finish with a layer of plain batter. Level surface and bake for 55-60 minutes, until a skewer inserted in centre comes out clean.
• 4.
  Set aside to cool in pan for 10 minutes before using paper to lift loaf out of pan and onto a wire rack to cool completely.
• 5.
  Meanwhile, to make icing, stir all ingredients in a small bowl until smooth. Drizzle over loaf and set aside to set.
• 6.
  Serve loaf cut into slices.