To prepare the custard, whisk together the eggs, sugar and cornstarch in a medium saucepan. Add the milk in a slow stream while whisking constantly over medium heat. Continue whisking or stirring until the mixture just begins to boil. Remove from heat and add the vanilla, stirring well.
Working quickly while the custard is hot, assemble the pie. Pour the Sambuca into a flat bottomed bowl. Spread a layer of custard in the bottom of the pie crust. Dip the Social Tea Biscuits individually into the Sambuca turning to coat both sides. Place a layer of biscuits on the hot custard, breaking the biscuits if necessary to fill in any large gaps. Continue layering custard and biscuits ending with custard (it's about 3 layers of custard to 2 layers of biscuits). You will not use the whole box.
Top the pie with a generous splatter of sprinkles. Using a vegetable peeler, place long curls of chocolate on top as well, if desired.
Chill pie without cover until set, about 45 minutes.
Variations: By changing the flavors of liqueur, cookies and/or custard many different but equally delicious pies can be created. A Frangelico-flavored pie in a prepared chocolate crumb crust is great! Use chocolate wafers and chocolate cookies and it tastes like a Bacci hazelnut candy. The combinations are limited only by your imagination and the contents of your liqueur cabinet!
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.