Place the chopped chocolate in a small bowl.  

Heat the cream until just barely simmering, and pour it over the chocolate.  Allow to stand for 5 minutes, then stir with a silicone spatula until smooth.  Cool the ganache until thick and spreadable.

Place the sugar, eggs, and salt in a mixing bowl and whip on medium-high speed until doubled in volume, and very pale and thick (5 to 10 minutes).  

Stir in the vanilla extract.  

Sift the flour and cocoa powder together, and add the mixture alternately with the melted butter, folding gently so the batter loses as little volume as possible.  

Refrigerate the batter (covered), for 45 minutes or until thickened.

Butter a madeleine pan generously, and refrigerate for 10 minutes.  

Preheat the oven to 375 degrees F.  

Scoop the batter into the prepared pan, filling each well about 3/4 full.  

Set a fresh raspberry (stem side up) into the center of each madeleine.  

Bake for 12-14 minutes, or until slightly crisp around the edges.

Cool in the pan for several minutes, then transfer to a wire rack to cool completely.  

Using a pastry bag fitted with a #5 tip, pipe a small amount of ganache into the cavity of each raspberry.  

Turn the madeleines over and dust with powdered sugar, for garnish.