How to get glacé icing right on a cake?

Question

Edited: Made the question a little less rambling.

I always thought that icing a cake was a pretty simple process. And then I tried to actually do it. Oh boy, how wrong I was!

It sounds simple enough. You take some icing sugar, wet it, mix it up until it's smooth, and then cover your cake with the stuff.

The problem is, when I do this, the icing always runs off the top of the cake.

Each time I make icing, I make it even drier than the last time. (Although never as little as 3 tsp per 100g. If you do that, it's just powder. I got 4 tsp to work though.) I've now reached the point where the icing is so thick and goopy that I struggle to mix it, and it's murder to stop it sticking to everything it touches - the bowl, the spoon, etc. And yet, it still runs off the cake!

Question: How to prevent glacé icing from running off the cake?

Obviously the pros always get this right every single time without fail. But how do they do that? Is it just that I need 30+ years of trial and error in order to instinctively "know" what the correct consistency is? Or is there something more specific?

PS. I realize I could use butter cream or fondant instead of glacé icing. (In fact, I'm probably going to do that at some point.) But plenty of professional cakes use glacé icing, so it must be possible, and I'm curious to know how.

PPS. No, the cake isn't particularly flat on top.

Answer 1

You have three options:

1. Prepare for drippage. If you're doing a lot of small items in particular, you set up a wire rack over a sheet pan, and just let it drip down. For the small items, you can dip into the glaze, then invert and place on the rack, like you would glaze a donut.

2. Add a barrier. Make a thicker icing that won't flow, and pipe right at the edge to give it a little bit of containment, then flood the top with the thinner icing. You'll need the cake nearly level for this to work well.

3. Pipe it on. You need an icing that's just thinned to the point where it will slump and flow back together, but not so thin it'll flow off. Use a piping bag (or plastic bag with the corner cut off) to make lines close enough together so the icing forms a solid covering. You may want to start at the outer edge and make a ring like #2, then work inward. This can work for more uneven cakes, as it doesn't need to be perfectly level, but it's more effort to get the consistency right.

Exact technique and consistency is going to depend on how thick (depth) you want the icing. It's always easier to thin it (doesn't take much added liquid) than to stiffen it back up.