Preheat oven to 180C. Grease and line the base and sides of a 30cm x 20cm tin with baking paper.
Sift the flours, bicarbonate of soda and cocoa into a large bowl and make a well in the centre.
Whisk together the eggs, sugar, vanilla, oil and yoghurt in a large jug. Add the flours and mix until smooth. Fold through the apple puree and raspberries.
Spoon the mixture into the prepared tin and bake for 30 minutes or until a skewer comes out clean when inserted in the centre. Allow to cool for 5 minutes in the tin before turning out onto a wire rack to cool completely.
Cut into squares and dust with icing sugar. Serve with extra fresh berries and reduced fat ice-cream.