Preheat the oven to 180. Cream together the butter and sugar until light and fluffy. Once pale in colour, beat in the egg yolks one at a time. Fold through the ground almonds, zest of the oranges, juice of one and the mash.
Whisk the egg whites until stiff peaks form. Then fold through the cake mix. Place in a lined 8-inch cake tin and bake in the heated oven for 40-45 minutes until golden and cooked. Once out and cooled, mix together the icing sugar and the juice of the orange and spoon over the cake. Serve straight away or leave the icing to set if you can.
