In a medium microwave-safe bowl, combine whipping cream, cream cheese, corn syrup, and liqueur. Microwave on medium power (50 percent) for 1-1/2 to 2 minutes or until mixture is smooth, stirring once. Add Ghirardelli 60% Cacao Bittersweet Chocolate Baking Chips; do not stir. Let stand for 5 minutes; stir. Microwave on medium power (50 percent) for 1 minute or until mixture is melted. Stir mixture until just smooth. (Do not over-stir or mixture will separate.) Cover surface with plastic wrap and chill for 15 to 20 minutes. Beat chocolate mixture with an electric mixer on low speed until light and fluffy. Cover and chill for 30 minutes or until easy to handle.
Line a baking sheet with waxed paper. Using a small cookie scoop or spoon, drop the truffle mixture into 3/4-inch mounds on the prepared baking sheet. Place one hazelnut in the center of each mound. Roll mounds into smooth balls, enclosing the hazelnut.
Meanwhile, in a medium microwave-safe bowl, combine chopped Ghirardelli Milk Chocolate Baking Bar and shortening. Microwave on medium power (50 percent) for 1-1/2 minutes. Remove and stir. If chocolate is not melted, return to microwave and repeat heating step, stirring every 30 seconds to avoid scorching. Stir until smooth.
Use a fork to dip the balls into the milk chocolate mixture, allowing excess chocolate to drip back into the bowl. Return truffles to baking sheet; chill for 30 minutes or until firm.
If desired, in a small microwave-safe bowl, place chopped Ghirardelli White Chocolate Baking Bar. Microwave on medium power (50 percent) for 1 minute. Remove and stir. If chocolate is not melted, return to microwave and repeat heating step, stirring every 30 seconds to avoid scorching. Stir until smooth. Drizzle melted white chocolate over tops of the truffles. If desired, sprinkle with a few grains of sea salt. Chill for 10 minutes or until firm.
Enjoy immediately or refrigerate in an airtight container for up to 3 days. If refrigerated, let stand at room temperature for 30 minutes before serving.
*To toast hazelnuts, preheat oven to 350°F. Spread nuts in a shallow baking pan. Bake for 5 to 10 minutes or until light brown, watching carefully and shaking once or twice. After toasting, to remove the flaky brown skin, place the warm nuts on a clean kitchen towel. Fold the towel over the nuts and rub lightly. The loose skins will flake off into the towel.