I made a lot of RI last night (thinned out to put on as a base for my cookies in red. I would love to use this same red as the top icing for the little decorations and things, although it will be too runny.

Can I do anything to thick'n it up?

A ton more powdered sugar Of course it depends on how much icing you are working with as to how much. You can even add a bit of cornstarch - I'd mix it w/the ps.

Thank you!