Prepare the Crust:
In a medium bowl, combine the chocolate cookie crumbs and melted butter. Stir until the crumbs are evenly coated. Spoon the mixture into the bottom of individual serving glasses or jars (about 6-8 servings). Press gently to form a compact layer. Set aside.

Make the Cheesecake Layer:
In a large bowl, beat the softened cream cheese and powdered sugar together until smooth and creamy. Add the sour cream, Baileys Irish Cream, and vanilla extract, and continue beating until fully combined. Gently fold in the whipped heavy cream until the mixture is smooth and fluffy.

Assemble the Trifles:
Spoon the cheesecake mixture into the prepared glasses, layering it on top of the cookie crust. You can add multiple layers of cheesecake if you prefer. Smooth the top with a spatula or spoon.

Prepare the Chocolate Ganache:
Heat the heavy cream in a small saucepan over medium heat until it begins to simmer. Remove from heat and add the chopped chocolate, stirring until smooth and glossy. Let the ganache cool slightly before spooning a layer of it over the cheesecake layer in each trifle.

Chill the Trifles:
Place the trifles in the refrigerator for at least 2 hours, or until they are fully set.

Garnish and Serve:
Just before serving, garnish the trifles with shaved chocolate or a dusting of cocoa powder. Add a dollop of whipped cream if desired. Serve chilled.