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 bursts, stirring until smooth. Let cool, then spoon into 12 small mounds (about 1 teaspoon each) onto a parchment-lined plate. Freeze for at least 15 minutes.
03 - In a medium bowl, sift together flour, cocoa powder, baking powder, baking soda, and salt.
04 - In a large bowl, whisk melted butter and sugar until combined. Add eggs one at a time, whisking well after each. Stir in the vanilla extract.
05 - Add half the dry ingredients to the wet mixture, followed by the buttermilk, then the remaining dry ingredients. Mix gently until just combined.
06 - Fill each cupcake liner with 1 heaping tablespoon of batter. Place a frozen chocolate mound in the center of each, pressing down 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 the tops are just set but the centers are still slightly soft.
08 - 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 to enjoy the molten center.