1. Preheat oven to 180C. Grease and line the base and sides of a 30cm x 20cm tin with baking paper.
2. Sift the flours, bicarbonate of soda and cocoa into a large bowl and make a well in the centre.
3. 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.
4. 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.5. Cut into squares and dust with icing sugar. Serve with extra fresh berries and reduced fat ice-cream.