Buttercream icing is a creamy sweet icing that is simple and affordable to make. It is usually used to dirty-ice cakes before applying fondant or the final layer of icing. Buttercream icing when used as the final layer of icing will not have the same polished flat appearance you will achieve with fondant and buttercream does not harden when piped like royal icing does. However, buttercream can be tinted into a variety of shades and colours like fondant or royal icing and buttercream creates a soft textured appearance when finished decorating.
Trim each cake tier with the serrated knife so that the top is level. You need the top of each tier to be flat so that when you stack each tier on-top of the other, the cake will be sturdy and not leaning to one side.
Ice each tier with a light layer of icing using the offset spatula. The icing does not need to look pretty you are applying this coat so that you do not get crumbs in the final layer of icing. This is called dirty-icing or crumb-coating the cake.
Apply an even layer of buttercream icing to each tier using the offset spatula. Take your time on this step. Ensure that you have an even layer of icing applied all the way around each tier as well as on top of each tier.
Press a sheet of quilted paper towel lightly against the icing. When you pull the paper towel away from the cake you will notice it left the quilted design as an impression into the icing. This step is optional but it is a simple way to add intricate design to the cake. Press the paper towel until all of the icing has the quilted design.
Tint the buttercream icing using food colouring gel. This step is optional if you do not want to use all white icing. Depending on the quantity of icing you need to tint will vary the amount of colouring you need. Start with very small amount and work your way up. If you use too much colouring you will be able to taste the bitterness of the dye in the frosting.
Attach a piping tip to an icing bag by pressing the tip over the plastic point and screwing a plastic coupler over the threads on the plastic point. Fill the piping bag half to two-thirds full with buttercream icing. Twist the end of the piping bag closed and press firmly against the icing.
Practice piping designs, monograms and flowers onto paper towels before starting to pipe your design onto the actual cake. It is very difficult to correct a mistake on the icing so take your time and pipe small lines at a time.
When adding colouring, dip a toothpick into the colouring gel and then run the toothpick through the frosting. You do not need a lot and for a standard batch that is all you will need. Whip the frosting to fully incorporate the colour into the icing.