We started baking these bars in November 1996. They were an immediate hit then, and they still are. Mocha-flavored chocolate on a rich shortbread base is a great combination. The instruction in the recipe for wrapping the still-hot pan of pastry in plastic wrap is admittedly unorthodox but necessary. When the pan is enclosed so that it is airtight, the topping steams and achieves a lovely, custard-like texture. These bars are tailor-made for entertaining and have the advantage of being made in advance on account of the pastry. We know these bars keep for 3 days, but if your household is like either of ours, you won't have them for that long.