Heat the oven to 350 degrees and line cupcake tin with papers or grease the tin.
Beat together the butter and sugar until light and fluffy. Add in one egg at a time and continue to beat until very light. Mix in the vanilla and the melted chocolate.
Sift together the flour and baking soda. Add the flour to the batter in two parts, alternating with the milk. Start and end with the flour.
Fold in the raspberries gently, taking care not to mush them.
Fill up the muffin tin ¾ of the way full and bake for 20-25 minutes or until wooden skewer comes out clean.
For the Raspberry Buttercream
Place jam and butter into the bowl of an electric mixer. Fit with paddle attachment and beat until smooth, creamy, light, and fluffy - about 2 minutes.
Add in powdered sugar one cup at a time until you reach your desired consistency and sweetness.