01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners.
02 - Place chopped dark chocolate and heavy cream in a microwave-safe bowl. Microwave in 20-second intervals, stirring between each, until smooth. Let cool slightly, then spoon into 12 small mounds (approximately 1 tsp each) onto a parchment-lined plate. Freeze for at least 15 minutes until firm.
03 - In a medium bowl, sift together flour, cocoa powder, baking powder, baking soda, and salt until well blended.
04 - In a large bowl, whisk melted butter and granulated sugar until thoroughly combined. Add eggs one at a time, whisking well after each addition. Stir in vanilla extract.
05 - Add half of the dry ingredients to the wet mixture, mixing gently. Add buttermilk, then incorporate remaining dry ingredients. Mix until just combined, taking care not to overmix.
06 - Fill each cupcake liner with 1 heaping tablespoon of batter. Place a frozen chocolate mound in the center, pressing lightly. Add 2-3 raspberries per cupcake, then cover with remaining batter, filling liners about 3/4 full.
07 - Bake for 14-16 minutes until tops are set but centers remain slightly soft to the touch.
08 - Let cool in the pan for 5 minutes, then transfer to a wire rack. Dust with powdered sugar and garnish with fresh raspberries and chocolate shavings if desired. Serve warm for optimal molten center effect.