(this makes enough to cover and decorate a 8″ or 9″ cake, and about 15 reg cupcakes)
3 egg whites
1/2 cup sugar (use white sugar for traditional buttercream, or brown for a caramel version)
150g butter, softened to room temperature (I used salted butter)
It is important that the butter be very soft but not melting.
1/2 tsp pure vanilla or any flavoring you want
food coloring, if desired
1. Whisk the egg whites over a double boiler. Ensure bowl is grease-free. Add the sugar and whisk lightly to combine. The idea here is to give the whites and sugar gentle heat from the steam of the simmering water, to dissolve the sugar.
2. Stir the contents of the bowl lightly with the whisk. Stir continously because you do NOT want the whites to get cooked.
3. Once the whites are ready, remove the bowl from the saucepan. While the whites are still warm, start whisking them, first at a low speed to allow them to froth up and then slowly moving up to high speed.
4. Whisk the whites until they have tripled in volume, are glossy and hold stiff peaks when you lift the beaters up.
5. Add the softened butter in tablespoonfuls. Beat until thoroughly combined before adding the next tablespoonful. The previously shiny and stiff meringue may now look disastrously soupy. This is normal.
6. Continue to beat the mixture on medium-high speed until it thickens. This can take anywhwere from 7 to 15 minutes, sometimes even longer. Ever so often, scrape down the bowl with your spatula.
7. After the buttercream thicken. Now, at this stage, you can add vanilla, flavoring and/or food coloring to the buttercream. Add in small amounts and blend in with the beaters on low speed. The frosting can be used immediately.
If the weather is very very hot and humid, bung the bowl in the fridge for a few minutes to stiffen up the buttercream before using. It also can be refridgerated for 4-5 days in a clean, airtight container.
If storing in the fridge, let the buttercream soften at room temperature for about an hour, and then whisk or beat until it becomes fluffy again before using.