Thanks for all your input... The following is the closest rec. I have found (just discovered it today.) Still, it's not the same (judging from the picture).

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Vanilla Slice

2 sheet ready-rolled puff pastry
1 cup caster sugar
3/4 cup cornflour
1/2 cup custard powder
3 cup milk
1 cup cream (SO THERE IS CREAM!!!)
60g (2 oz) butter
2 t. vanilla essence/extract
3 egg yolks

Icing: (WHICH IS NOT ON THE ONE IN THIS FRENCH BAKERY!)

1 1/2 cups icing sugar
1/4 cup passionfruit pulp
2 t. lemon juice
15g (1/2 oz) butter softened

Preheat the oevn to very hot 240C/475F/Gas 9. Grease 2 baking tray with oil. Line the base and sides of a shallow 23cm/9 in square cake tin with foil, leaving the foil to hang over the 2 sides. Place the pastry sheets on the baking trays. Prick all over with a fork and bake for 8 minutes, or until golden. remove from oven and trim each pastry sheet to a 23cm/9 in square. Place one sheet in the tin, top-side-down.

Combine the sugar, cornflour and custard powder in a pan. Gradually add the milk and cream and stir until smooth. Stir the mixture constantly over med. heat for 2 min., or until it boils and thickens. Add the butter, vanilla and stir until smooth.

remove the mixture from the heat. Whisk in the egg yolks unil combined. Spread the custard over the pastry in the tin and cover with the remaining pastry to-side-down. Allow to cool.

To make the icing, combine the icing sugar, passionfruit pulp, lemon juice and butter in a heatproof bowl. Place the bowl over a pan of simmering water and stir until the icing is smooth and glossy. REmove from the heat. Lift the slice out of the cake tin, using the foil 'handles' to help you. Spread the icing over the top of the slice and leave it to set before cutting into squares with a shapre serrated knife.