Heat the oven to 350 degrees and line a cupcake pan with papers. Beat together the butter and sugar until light and fluffy. Add 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 powder. Add the flour to the batter, alternating with the milk, starting and ending with the flour. Fold in the raspberries gently, taking care not to mash them. Fill up the muffin pan 3/4 full, and bake for 20-25 minutes, or until a wooden skewer comes out clean. For the butter cream, place the jam and butter into the bowl of an electric mixer. Fit with a paddle attachment and beat until smooth, creamy, light, and fluffy, about 2 minutes. Add powdered sugar, one cup at a time, until desired consistency and sweetness is obtained. Frost cooled cupcakes.