In a medium saucepan, combine the cream, milk, sugar, Kahlua and espresso powder. Bring to a gentle boil over medium heat. Remove from the heat.

In a medium bowl, beat the egg yolks until thickened. Whisk 1 cup of the hot cream into the egg yolks. Gradually add the egg mixture in a slow, steady stream, to the hot cream. Cook over medium-low heat, stirring constantly, until the mixture thickens enough to coat the back of a spoon, about 5 minutes. Remove from the heat and strain through a fine mesh strainer into a clean container. Cover with plastic wrap, pressing down against the surface to keep a skin from forming. Refrigerate until well chilled, at least 2 hours. Remove from the refrigerator and pour into the bowl of an ice cream machine. Freeze according to the manufacturer's instructions. Transfer to an airtight container and freeze overnightt, until very firm.

Line 2 small baking sheets with aluminum foil. Freeze until very cold, at least 2 hours. Remove 1 sheet. Dip a 1-inch (about 1 1/2 teaspoons) scoop into a cup of hot water.

Working quickly, scoop the ice cream into 12 balls as round as possible, and release each onto the frozen baking sheet to prevent from melting. Return the sheet to the freezer.

Remove the second sheet from the freezer and repeat the process to form 12 more ice cream balls. Return the sheet to the freezer.

Wrap the sheets in plastic wrap and stick 1 round toothpick in the center of each ice cream ball. (Reserve the remaining ice cream for another use, or double the chocolate shell recipe and use remaining the ice cream to create a larger number of bonbons.) Freeze the balls until very firm, overnight.

To make the chocolate dip, in the top of a double boiler or in a metal bowl set over barely simmering water, combine 14 ounces of the chocolate and the shortening. Melt over low heat, stirring, until temperature reaches 116 to 118 degrees F, or feels fairly warm but not hot to the touch.

Remove the chocolate dip from the heat and stir in the remaining 2 ounces of chocolate. Continue stirring until the chocolate reaches 80 degrees F or feels cool to the touch.

Return to low heat and cook, stirring, until the temperature rises to 85 to 87 degrees F, or feels barely cool. Remove from the heat.

Remove 1 sheet of ice cream balls from the freezer. Fill a 2-tablespoon measure with melted chocolate. Working quickly, hold 1 ice cream ball by the toothpick over a clean bowl. Pour the chocolate over the ball, turning to coat, catching the excess in the bowl and letting the excess chocolate drip off. Place the coated bonbon on the foil-lined sheet and repeat with the remaining ingredients. Return to the freezer until ready to serve, at least 30 minutes.

Before serving, place in a large, decorative bowl and remove the toothpicks.