Preheat oven to 180 degrees C. Line a 12-cup-muffin-tin with patty cups.
Cream the butter or margarine and white sugar together until pale and fluffy. Gradually add small amounts of beaten egg, beating continuously. In a small bowl, combine cocoa powder and hot water. Stir cocoa mixture into batter. Fold in flour using figure of eight movements. The batter should slowly drop off spoon when lifted from bowl - if the mixture is too stiff, add a small amount of water. Divide mixture into 12 muffin cups.
Bake for 15 to 20 minutes, or until well risen and firm to touch. Allow to cool.
To make the icing, cream the butter or margarine until soft. Gradually add the sifted icing sugar and vanilla. Mix until smooth.
Cut circles from tops of the cakes, and cut in half again to resemble butterfly wings. Put a small amount of jam in the cut out hole, and cover with a teaspoon of icing. Place the wing shapes into the icing so they sit like butterfly wings.