Swiss meringue buttercream

Pasteurize the egg whites yourself, or use pasteurized liquid whites and only dissolve the sugar.

The ratio is one part egg white, two parts sugar, two parts butter.

Put the clean egg whites in a bowl with no fat in it -- fat is the enemy of meringue -- and add all the granulated sugar.

Set the bowl on a bain-marie and cook to 145 degrees Fahrenheit, whisking, until no grains of sugar remain.

Whip the whites and sugar to a fluffy meringue. At this point it could serve as a Swiss meringue for souffles, meringue cookies or macarons.

Start the mixer low and let it climb, then go to medium-high; whip until the bottom of the bowl feels room temperature, because butter added too soon makes buttercream soup.

Whip until it is really fluffy and the meringue almost pulls away from the bowl, and check it is stiff before adding butter.

Keep the speed low and add the butter in pieces, nothing too small.

Whip until it comes together to a whipped cream consistency: creamy, with a bit of shine, not runny and not falling off the whisk. If it looks granular or like cottage cheese, chill it briefly and whip it again.

Add a small amount of fat-based gel colouring after the butter, never water-based, and mix it in.

To knock out the air bubbles the whisk leaves, put it back on the machine with the paddle attachment on very low speed for five minutes, with enough buttercream to cover the paddle. Needed for smooth iced cakes rather than for piping.