Preheat the oven to 150 degree C (300 F)
Roughly chop the nuts
Add all ingredients (except the blueberry part) in a big bowl and stirring until well combined and you have a sticky mass
Add half of the mixture into a rectangle or square baking pan and press it down with the back of a spoon
Add the blueberries and powder to the other half and mix well
Put on top of the mixture in the pan and press down as well
Bake for half an hour and let cool in the pan
For the icing mix the sugar with the juice and some powder and decorate the bars
Cut in bars and enjoy