Preheat the oven to 200oC, gas mark 6. Place a baking tray in the oven to preheat.
To make the pastry, place the flour, sugar and butter in a food processor and blitz until its just starts to clump together. Transfer to a 23cm fluted flan tin and press into the base and up the sides. Place on a baking tray and bake for 10 minutes.
Meanwhile, add the 100g walnuts to the same food processor and blitz until fine, add all the remaining filling ingredients, except the whole walnuts and blitz until smooth. Pour into the pastry case and scatter over the whole walnuts. Bake for 25-30 minutes until golden. Cool before removing from the tin.
