Mix flour, rind, salt and egg on high speed until a dough is formed.
Divide the dough into 1/3 and 2/3 parts, wrap well in foil and chill for minimum 1/2 hour.
In the meantime, heat the sugar for the filling until it caramelises to a very light brown.
Heat the cream (can be in microwave) and add it to the caramel, stirring rapidly.
Add the honey, heat until it reaches a rolling boil.
Add nuts and stir well. Remove from the heat and allow to cool.
Mix well and allow to cool.
Roll out the larger of the pastry dough rolls and fit into a greased 24cm springform pan to cover the base and sides.
Pour in the cooled filling.
Roll out the remaining dough to form a lid for the cake. Put on top of the filling and join the edges well.
Paint the top of the cake lightly with whisked egg yolk.
Cook the cake at about 180 degrees for 50-60 minutes.
Take the cake out of the oven and allow to cool. Do not remove outside of tin until cool! The cake should be totally cold before serving- I put mine in the fridge on the base, and only take it off the base once it's cold and the filling has set. Otherwise if the filling is still hot the bottom will sag when you pick it up.