How do I make icing that is not too runny?

Icing consistency is entirely a ratio problem, and it is asymmetric: adding sugar to thin icing works, adding liquid to thick icing works, but both are easier if you start from the dry side and creep towards the wet.

What you'll need

• Icing sugar
• Butter for buttercream
• Sieve
• Electric whisk (optional)

Step by step

1. Sieve the icing sugar. Every time.Icing sugar clumps in storage, and lumps will not beat out. This is the one step that cannot be skipped.
2. For buttercream, beat softened butter alone until pale.Two or three minutes. Pale, aerated butter gives a lighter buttercream than sugar beaten into cold butter.
3. Add icing sugar at roughly twice the butter weight, in stages.100g butter to 200g icing sugar. Add it a third at a time and beat between additions.
4. Add liquid one teaspoon at a time, only if needed.Milk, cream or vanilla. It is astonishing how little is needed, and how fast it goes from stiff to soup.
5. For glacé icing, put sugar in a bowl and add water drop by drop.Around 1-2 teaspoons of water per 100g of icing sugar. Stir thoroughly between additions before deciding it is too thick.
6. Judge consistency with the ribbon test.Lift the spoon — the drizzle should hold its shape for a few seconds before sinking back in. That is right for drizzling and coating.
7. Fix runny icing with more sieved sugar, not by chilling.Chilling firms it temporarily; it slackens again at room temperature. Sugar is the actual fix.
8. Cool cakes completely before icing.Any warmth melts buttercream on contact and it slides off. This is the most common cause of icing 'failing'.

Tips

• Cream cheese frosting is loose by nature. Use full-fat block cream cheese, never the spreadable tub kind, and do not over-beat it.
• Buttercream that looks split has warmed up. Chill for fifteen minutes and re-whip and it comes back together.
• For piping that holds sharp edges, make the buttercream slightly stiffer than feels right — it softens in a warm room and in your hands.

Common mistakes

• Adding liquid by the tablespoon — Icing goes from thick to unusable in a moment. Teaspoons, or drops for glacé icing.
• Skipping the sieve — Lumps of compacted icing sugar do not dissolve and will block a piping nozzle.
• Icing a warm cake — The butter melts on contact and the icing slides off and soaks in. Completely cool means completely.

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