Let's make a striped Christmas cake by covering a cake with buttercream stripes and piped Christmas trees! I'm using pink and mint green buttercream but of course, you can use bright red and green if you want something more traditional. Ask me any questions below in the comments and you can watch a video of this tutorial below as well.
To make a striped Christmas cake, start by making the stripes! First, smooth the frosting on your cake with a straight edged cake comb. I'm using my 4 Minute Buttercream for this cake and for all of my cakes! This doesn't have to be perfectly neat but the sides need to be straight and the top should be level. The frosting needs to be thick enough that the grooves on your striped cake comb can go through it without reaching the crumb coat underneath.
It's easiest to touch up any indents in the frosting now, rather than after using the striped cake comb. Spread more frosting over the indents and scrape again with your straight cake comb until fairly smooth. Then switch to a striped cake comb. These can be made of plastic, acrylic or metal and I find that metal works best for me.
The first few scrapes will look terrible! You'll see messy texture in the stripes and the grooves. Keep scraping and you'll imprint the grooves of the cake comb into the frosting on the cake.
These grooves need to set before adding another colour so put the cake in the freezer for 15 minutes. Meanwhile, prepare piping bags with the other colours you're going to use for your stripes. You'll use an offset spatula and a straight edged cake comb for the next step. A little bowl for the frosting you scrape off the cake is useful, too.
After 15 minutes in the freezer the frosting will be cold and firm. Pipe the next colours into the striped grooves using the piping bags you prepared. Hold the piping bag very close to the surface of the frosting within the grooves, squeezing until you see the frosting bulging out to fill in the stripe groove. Spin the turntable slowly to fill the groove all the way around the cake.
There are two things that can go wrong with striped cakes. The first is not completely filling these grooves with these colours. When you scrape next, the wrong colour can get into the groove and cause random flecks within that stripe.
The other thing is not getting the frosting smooth with the striped cake comb before adding these colours. These colours will then get into any air pockets or indents or air bubbles in that first colour of frosting. You'll see random pink or green specks within the white stripes.
After filling in the grooves, switch to a straight-edged cake comb and scrape around the cake. With each scrape you'll push the colours into the grooves and you'll also take off the excess. You'll flatten the coloured frosting until it's level with the striped grooves of the first colour. This makes all of the stripes perfectly flat! It's a long process though, so keep scraping again and again.
After each scrape, wipe off the frosting from your cake comb into that little bowl. I like to start with a plastic cake comb because it's the quickest to use but once the frosting starts to get smooth, I switch to a metal cake comb. This gives me the smoothest frosting. The other benefit of a metal cake comb is that you can heat it with hot water or a blowtorch. The hot metal will melt the very outer layer of the frosting so it comes very easily off the cake, leaving a super smooth surface underneath.
Okay, let's talk about all of these imperfections: why they happen and how to fix them. These flecks of green and pink within the white stripes happen because there were little indents in the white stripes. Those were then filled in when I scraped the colours around the cake with my straight edged cake comb. Keep scraping a few times to try to scrape the flecks off. Very deep flecks can be scooped out with an offset spatula or the corner of your cake comb. Then spread white frosting into the gouges and scrape that smooth.
By now the striped frosting will probably have set since the cake was in the freezer so it's very cold. Using a hot metal cake comb is the easiest way to scrape around the cake when this happens.
Before levelling the uneven top edge, put the cake in the fridge for 15 minutes to set that frosting. When it's cold and firm you can slice it off the cake with a knife. This will give you a very sharp top edge around the cake and prevent smudges or stains of coloured frosting on the top of your striped Christmas cake.
Now let's add some details. For a colourful border put your leftover frosting into piping bags fitted with a star-shaped tip. I'm using a 1M piping tip in each of three piping bags. Pipe a little dot and then pipe a circle, swiping away at the end to leave a C shape. Switch to the next colour and pipe another C to overlap it.
If you only have one piping tip just use only one colour for all of this piping. The dot at the beginning raises the first C so that it sits at the same angle as the rest of the piping. This is called a rope border. It's a great way to use up leftover frosting and also adds height and colour and detail to the top of a cake.
To add Christmas trees you can use any star-shaped piping tips. To pipe the trunks I recommend using one with short prongs very close together, like a #363.
For the green parts of the trees I recommend using star tips with longer prongs more spaced apart from each other. These are a #18 and #16:
The technique for these trees is very simple and very forgiving. Pipe from the middle of the tree, above the trunk, going outwards and downwards. Start with the longest line and then work your way up. Each line should be shorter and shorter so that the trees get narrower towards the top.
To learn all about how to pipe stripes and more advanced stripe techniques like multi-coloured stripes and peek-a-boo designs, check out my Layer Up program, which takes you through three layers of skills and techniques to go from a beginner to a professional cake decorator or join my All You Can Cake membership for access to everything on my cake school!
You can watch a vide of this tutorial on a Striped Christmas Tree Cake:
