Pre-heat oven to 180ºC and line a loaf tin or a 20cm round tin.
Cream butter and sugar on speed 8 for 20 seconds.
Add eggs and mix on speed 4 for 10 seconds.
Add mashed bananas and vanilla and mix on speed 4 for 5 seconds.
Add flour, bi-carb soda, milk and mixed spice and mix on speed 4 for 10 seconds (if too thick add more milk).
Add currants and nuts and on speed 4 for 5 seconds.
Bake for 40-60 minutes or until browned, the top springs back when pushed, sides have shrunken back from the tin a little and a skewer tests clean.
When cake is cool ice with maple buttercream.
Cream butter on speed 4 for 2 minutes or until it becomes pale yellow in colour.
Add icing sugar and maple syrup and mix on speed 4 for 30 seconds.