Ingredients:

  • 1 cup (200g) granulated sugar
  • 5 large (150g) egg whites, at room temperature
  • 1/4 teaspoon (1.5ml) cream of tartar
  • 1/2 teaspoon (2.5ml) salt
  • 1 cup (2 sticks or 226g) unsalted butter, very soft but still cool, cut into cubes
  • 1-2 teaspoons (5-10ml) vanilla extract

Instructions:

  1. In the bowl of your stand mixer (or heatproof bowl), combine the egg whites, sugar, cream of tartar, and salt.
  2. Place the bowl over a saucepan of simmering water (making sure the bottom of the bowl doesn't touch the water). Whisk constantly until the sugar is completely dissolved and the mixture is hot to the touch (about 160°F/71°C if using a candy thermometer).
  3. Remove the bowl from the heat and immediately transfer it to your stand mixer fitted with the whisk attachment. Beat on medium-high speed until stiff, glossy peaks form and the bowl is completely cool to the touch (this may take 8-10 minutes). The meringue should be very stable and holding its shape.
  4. Reduce the mixer speed to low. Add the softened butter, a few cubes at a time, allowing each addition to be fully incorporated before adding more. The mixture may appear curdled or separated at first – don't panic! Keep mixing, and it will come together.
  5. Once all the butter is added, increase the mixer speed to medium-high and whip for 2-3 minutes, or until the buttercream is light, fluffy, and smooth.
  6. Mix in the vanilla extract or other flavouring.
  7. Use immediately or store in an airtight container in the refrigerator for up to a week. Re-whip to restore its smooth texture before using.