Makes 6 individual tartlets, or one 10-inch tart. Intensely, unmistakably and irresistibly chocolaty. The chocolate pastry shell is a cross between a cookie crust and a buttery, flaky pie dough, and the filling is a creamy bittersweet chocolate truffle concoction given crunch with cubes of milk chocolate, white chocolate, and the crackly biscotti. The tartlet is very sophisticated, very elegant, and totally over the top. From Julia Child's "Baking with Julia", contributing baker David Ogonowski.