Line the base and sides of a shallow 25cm square cake tin with aluminium foil - with some of the foil extending over two of the sides , this will help with the lifting the slice out of the tin later on . Then brush 2 oven trays (or use the same one twice) with oil ready to cook the pastry sheets on .

Place the pastry sheets , one per tray , onto the prepared oven trays and prick pastry all over with a fork , so to help the pastry from rising too much . Now bake in the preheated oven for about 8-10 minutes or until pastry is golden and crisp .

Once cooked remove from heat and place cooked pastry sheet , top side up , flat side down , into the prepared foil lined tin and set aside to cool whilst you make the filling .

TO MAKE THE FILLING : Combine the sugar , cornflour and the custard powder into a medium saucepan and gradually add the milk and the cream ; stirring constantly until smooth .

Stir mixture continuously over medium heat on stove top for a few minutes or until the mixture starts to boil and thicken ; now add the 60g of butter and use vanilla essence and stir until smooth .

Now remove from the heat and whisk in the egg Yolks until well combined , thick and smooth .

Now spread the prepared custard mix into and all over the cooked , cooled pastry in the foil lined tin , spreading it evenly .

Next place the remaining cooked , cooled pastry sheet , top side up and rough side inways , onto the custard on the bottom pastry sheet , and push down gently to seal them together . Leave to cool and set whilst you prepare the icing mixture .

To MAKE THE ICING MIXTURE : Combine the icing sugar the passionfruit pulp the lemon juice and the extra 15g of butter into a heatproof bowl and stand the bowl over a pot of simmering water , but do not let the water touch the bowl , and stir them all until over the heat until the icing is smooth and glossy , once ready remove from the heat .

Either Carefully , using the foil hangover bits to help , lift the prepared slice from out of the cake tin , and spread the prepared icing mixture all over the top of the slice evenly . Now leave it to allow it to cool and set in the fridge OR leave it in the cake tin to ice it and let it set before cutting or removing it from the cake tin .

Once cooled and set , cut the slice into even square pieces using a long sharp serrated knife . Careful it can get messy at times lol