You can use any flavor cupcake you want as chocolate goes with just about everything. I made a light chocolate flavored buttercream frosting and piped it on.
To make the butterflies you will need one plastic squeeze bottle each for white, milk, and dark chocolate. Find a butterfly design you like or make your own. Place a piece of parchment paper on top of the design and trace/color each wing sepeartely with witchever chocolate you want. I prefer to use a vanilla whit chocolate for smaller designs because it hardens faster and holds a little better than milk chocolate. Leave the chocolate to harden over night and attach with a glob of white chocolate, It will take a few minutes for it to hold so you might want to find something to prop up each wing while you wait.
The ones in the picture stayed out for 1 whole month just to see how long they would last; the chocolate help up so you shouldnt have any breakage worries!