How do I make this chocolate? I already have it made and need it to be chocolate. Has anyone done this?

YOu could try dissolving a bit of cocoa powder in boiling water and adding it to the icing.

Or....melt some chocolate and beat it in. I've done that with white chocolate and it worked out well.

Per their book: stir in 2 to 3 oz of melted, body temperature semisweet chocolate per 1 cup of icing, mix until smooth and completely blended, scraping down the sides of the bowl to prevent the chocolate from hardening and causing unmelted flecks in the buttercream.

I have not tried it myself though. Good luck, P