Preheat your oven to 350°F and line a cupcake tin with liners. In a large mixing bowl, combine the flour, sugar, cocoa powder, baking powder, baking soda, and salt. In another bowl, whisk together the melted butter, eggs, and vanilla extract. Gradually add the wet ingredients to the dry ingredients, alternating with the buttermilk. Mix until smooth and well combined.

Fill each cupcake liner about two-thirds full with the batter. Bake in the preheated oven for 18-20 minutes or until a toothpick inserted into the center comes out clean. Allow the cupcakes to cool in the tin for 10 minutes, then transfer them to a wire rack to cool completely.

In a saucepan, heat the heavy cream over medium heat until it begins to simmer. Remove from heat and add the chopped dark chocolate and butter. Stir until smooth. Puree the raspberries in a blender and strain to remove seeds. Stir the raspberry puree into the chocolate mixture until fully incorporated.

Once the cupcakes have cooled, use a small spoon to carve out a small hole in the center of each cupcake. Fill the hole with the raspberry ganache and top with the removed piece of cupcake. Optionally, frost with additional ganache or your preferred frosting and decorate with toppings like fresh raspberries or chocolate shavings.

Store any leftover cupcakes in an airtight container at room temperature for up to three days or refrigerate for up to a week. For longer storage, freeze the cupcakes without the ganache filling and frost them before serving.