Basic Buttercream Frosting
combine 4 large egg whites (at room temperature) and11/ cups caster sugar in the bowl of a mixer; heat over low and whisk until sugar is dissolved. remove from heat and beat on medium-high for 10 minutes. While mixing, add 450 g butter (cubed, at room temperature) one piece at a time; beat until well combined. add 1 tsp. vanilla extract and food coloring of choice; mix well.