Prep 35-40minMakes about 3 cups

Ingredients

4 egg whites (from 59g/2oz eggs), at room temperature
220g (1 cup/7¾oz) caster sugar
250g (9oz) unsalted butter, cut into 8 equal portions, at room temperature
Good pinch of salt, or to taste
1 teaspoon natural vanilla essence or extract, or to taste
Food colouring gel of your choice (optional)

Method

1. Combine the egg whites and sugar in a large heatproof bowl and place over a saucepan of barely simmering water (make sure the bowl does not touch the water). Stir with a whisk until the sugar is dissolved and the mixture reaches 65°C/150°F on a sugar thermometer.
2. Transfer the mixture to the bowl of a stand mixer and whisk on medium-high speed with the whisk attachment for 10-15 minutes or until very thick and glossy and the mixture has cooled completely to room temperature.
3. Replace the whisk attachment with the paddle beater. Beat on medium-high speed using the paddle beater for about 10 minutes adding a portion of butter one at a time and beating well after each addition until completely incorporated and smooth before adding the next portion of butter. If the mixture becomes lumpy or looks slightly curdled at any stage increase the speed to high and beat until smooth before adding the next portion of butter.
4. Reduce speed to medium-low and beat for 3-4 minutes and the mixture is smooth and creamy. Beat in the salt and vanilla. Tint with gel colour to desired colour if using. Use imediately.