In a small saucepan over medium heat, warm heavy cream and unsalted butter until simmering. Remove from heat and stir in semi-sweet chocolate chips until smooth. Allow the mixture to cool slightly, then refrigerate for at least 2 hours or until firm enough to scoop.

Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners. In a large bowl, whisk together cake flour, unsweetened cocoa powder, baking soda, and a pinch of salt. In another bowl, cream unsalted butter and sugar until fluffy before adding egg and vanilla extract. Combine with sour cream and alternately mix in the dry ingredients and milk until just combined.

Spoon the cupcake batter into the prepared liners, filling each about two-thirds full. Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center comes out with moist crumbs. Allow the cupcakes to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.

Once the cupcakes have cooled, use a small knife or a cupcake corer to create a pocket in the center of each cupcake. Place a ganache truffle in each pocket, then replace the top portion. Refrigerate the filled cupcakes for about 15 minutes to help the truffles firm up.

In a mixing bowl, sift together powdered sugar and cocoa powder. Beat softened cream cheese until smooth, then mix in softened unsalted butter and shortening until well blended. Gradually incorporate the dry ingredients along with vanilla extract, mixing until the frosting is light and fluffy.

Using a spatula or a piping bag, generously spread or pipe the creamy frosting onto each cupcake, covering the tops completely. Garnish with chocolate curls before serving.