Glaze is more for donuts. It's shiny and hard but soft.

You can buy royal icing mixes or make the original recipe with egg whites and icing sugar.

I cheat and use meringue powder as I know it's safe for people who can't do uncooked egg. And I cheat again by using pavlova egg as meringue powder as meringue powder is ridiculously expensive and is the lesser of two evils when it comes to additives.