Mix together the flour, sugar and ground almonds.
Add the cold butter and mix together with your finger tips until the mixture looks like breadcrumbs.
Add the egg and vanilla essence and mix until the mixture just comes together.
Roll into two rectangles and place in a tin.
Let it rest in the fridge for one hour.
Spread a thin layer of raspberry jam onto one of the rectangles leaving half an inch border.
Brush the egg yolk on this border and place the second rectangle on top.
Lightly press down the top layer, pressing firmly on the edges.
With a fork prick the top layer all over.
At 160C bake for 30 minutes until a light golden brown.
Once cooled, turn upside down and spread a layer of very thick water icing so that you cannot see the pastry underneath.
To finish, sprinkle dehydrated raspberries and chopped pistachios on top, then trim the edges and slice into rectangles.