Put the egg whites in a large bowl and beat briefly to break them down
2 large egg whites
Add the icing sugar a tablespoonful at a time and beat thoroughly in between (or leave the mixer on if using). Stop when you get to a mixture that holds its shape and forms soft peaks.You may not need all the icing sugar. It will depend on the size of your eggs
500 g icing sugar,
Add the glycerine and beat for 5 minutes to get a good shine
1 teaspoon glycerine
Tip or spoon the icing onto your marzipanned cake and spread more or less evenly over the top and sides with a palette knife. If you want a snow effect, put the flat blade of the knife on the icing and pull off quickly. (It's a bit like dabbing at the icing)
Decorate with whatever you like - or whatever the supermarket has the week before Christmas
Notes
Everyday Cooks tips:
Use the freshest eggs that you have as they aren't cooked. The sugar preserves them, but I like to start with freshest possible
You don't need to sieve the icing sugar if you open a fresh pack that is in date and hasn't got damp (if it's in a box it will be fine). If you're using icing sugar from an opened bag you will need to sieve it
Glycerine keeps the icing soft but, if you're making royal icing for a tiered cake, leave it out as the icing will need to support the weight of the other cake(s).