For Chocolate Cupcakes: Preheat oven to 350 degrees F. Pour boiling water over chocolate. Set aside to cool to room temperature. In a stand mixer, beat butter until whipped and creamy. Add sugar, beat until fluffy. Add eggs, one at a time. Finally, add melted chocolate. In a large bowl sift together flour and baking soda. Alternate between the dry ingredients and the sour milk, until a light and well combined batter forms. Turn into a tray of lined cupcake tins. Bake for about 25 minutes or until tester comes out clean. For Icing: In a stand mixer combine butter and sugar until thick and creamy. Spread over each cupcake, once completely cooled and top with Ghost Peeps immediately before the frosting sets.