Swiss meringue buttercream is a smooth and creamy frosting made from egg whites, sugar, and butter. The process begins by heating egg whites and sugar together until the sugar dissolves, then whipping the mixture until it forms stiff peaks. This creates a stable meringue that is then combined with softened butter to achieve a rich and velvety texture. This type of buttercream is known for its lightness and less sweet flavor compared to traditional American buttercream. It is often used for decorating cakes and cupcakes, providing a perfect base for various flavors and colors.