To make the loaf
1. Preheat the oven to 200C/400F/gas mark 6.
2. Cream together the brown sugar and the butter.
3. Stir in the eggs, bananas, flour and bicarbonate of soda.
4. Mix in the sour cream.
5. Spoon the mixture into a lined loaf tin and bake for 1 hour. Leave aside to cool.
To make the icing
1. Melt together the butter and brown sugar.
2. Stir in the sour cream and boil for 2 minutes.
3. Add the icing sugar and spread over the cooled loaf.