Buttercream icing is a mixture of fat, usually butter, and confectioners sugar. You can add cream, eggs and flavourings such as vanilla or chocolate as desired. Use buttercream for icing cakes and making decorative accents. The ideal buttercream is smooth, light and fluffy, never grainy or lumpy. To prevent lumps, sifting the icing sugar thoroughly is necessary. Make sure the butter is at room temperature before you begin. Beat the butter until it's soft, then add your other ingredients slowly, scraping the sides of the mixing bowl as you go.
Remove the icing from the refrigerator, if applicable, and allow it to come to room temperature.
Place the lumpy icing in the bowl for your standing mixer if you have one. Otherwise, using a hand mixer is fine.
Turn the mixer on a medium setting and whip the icing for a few minutes. Stir the icing around with a spoon to test the icing's consistency. If there are still lumps, continue to mix.
To prevent buttercream from softening, use confectioners sugar derived from cane rather than sugar beets. Stabilise the icing with 1 to 2 tbsp of meringue powder. Store buttercream in the freezer. When you're ready to use it, thaw it completely, then beat it with an electric mixer.