I've had several queries lately about my recipes for icing and cookies, so I thought I'd create a couple of posts to direct people to.
I thought I could deal with the icing and move onto the cookie recipe very quickly, but it turns out I have a LOT to say about royal icing, which might give the impression I know a lot about it. Do not be deceived by this.
I use royal icing for all my cookies, as it dries hard and can be used very stiff, for piping 3D shapes, watered right down so it will flow over a flat surface and smooth itself out, or anything in between. It works perfectly as a 'glue' to secure bits and pieces of this and that you might want to stick to a cookie.
Royal icing is basically powdered white sugar with some form of egg white added so it dries hard. It can be made fresh, by whipping the egg whites and adding the sugar, or in a range of pre-made steps using pasteurised, fresh or dried egg white. The latter can also come in the form of meringue powder (which also contains cornstarch as an anti-caking agent). Often recipes contain other ingredients such as cream of tartar to aid in the strength of the egg whites.
It takes colouring and flavouring well, and can be softened with glycerine or corn syrup so it's not such a hard, crunchy bite. It keeps very well while fresh and can be refrigerated or frozen, and though it separates and looks odd when it's been sitting a while, a really good mix will bring it back to perfect again.
Looks really weird, but it'll be fine once it's whipped back up!
Once dried hard, pieces of royal icing can be kept for years without deteriorating, though sunlight can affect the colours, moisture can make it crumble and soften, and of course if it's sitting on a biscuit the fat can leach into the icing causing splotching and softening.
As it's mostly sugar, and sugar is bactericidal, it's very difficult for icing to go 'off'. This is why royal icing transfers, where a small decoration is made seperately, left to dry and then added to the cookie or cake later, are an excellent way of working ahead, as they can be stored foralmostever - I still have a little boxful of these eggs I made for my Owl Egg tutorial over at Cookie Connection.
In the UK we have a brand of English grown sugar called Silver Spoon; they make a ready made royal icing powder to which you just add water and whatever colours and flavours you want. It contains dried egg white and an anti-caking agent called tricalcium phosphate. This is what I prefer to use, as it's just so simple, with my particular mix of flavourings such as lemon juice or salt.
So, if you're looking for a royal icing recipe, and ask me, I'll just tell you to buy a box of Silver Spoon, because the sugar's grown not far from where I live and it's by far the easiest way to do it.
But that's not helpful if you don't live here, so here are a few alternatives:
Mike at Semi Sweet uses meringue powder
LilaLoa uses dried egg whites
Delia Smith uses fresh egg whites