Heat oven to 160C/140C fan/gas 3.
Butter a 22cm round loose-bottomed
cake tin and line the base with baking
parchment. Beat the butter and caster
sugar together in a large bowl until it
is light and fluffy. Gradually pour in and
beat the eggs, a little at a time, until
you have used two-thirds, adding flour
if it curdles. Fold in the remaining egg,
the ground almonds and finally the flour,
and combine everything gently.
Add two-thirds of the apples to the
cake mixture and all the blackberries.
Turn the mixture into the prepared tin
and smooth it out evenly. Scatter the
remaining apples over the surface of the
cake. For the topping, sprinkle over the
cinnamon, demerara sugar and butter.
Bake for 50-55 mins or until a skewer
comes out clean. Remove the cake from
the oven and scatter on the toasted
hazelnuts. When the cake is cool, dust
lightly with icing sugar. Serve in slices.