Add cinnamon sugar and butter together and melt.
Add Flour, Sugar and baking powder to a bowl and mix
Add the eggs, milk and vanilla until just combined.
Stir in the melted butter and fold in the mashed banana
Pour the batter into a baking tin, dollop on cinnamon mixture and swirl throughout.
Bake 180C/(160C fan) 40-45 mins - or until the top is golden and a toothpick comes out clean.
Make the glaze, and spread over the cake whilst still warm.
Leave cake to cool in the tin.
