Smash cakes are popular for first birthday celebrations and these little cakes are perfect for small gatherings, too! They're easier than you think to make. I'll show you how to make them with and without tools like a turntable and cake comb.
Bake your smash cake layers
First, bake your smash cake layers. These are typically four or six inches but you can use the techniques in this tutorial for any size cake. I'm using my Small Batch Chocolate Cake recipe to make 4" layers:
Prepare your smash cake layers by letting them cool completely, which takes about two hours. Then if the tops are domed you can level them with a serrated knife like a bread knife.
For the easiest assembly and neatest frosting, wrap these in cling film or plastic wrap. Then put them in the fridge for about an hour so that they chill.
Assembling smash cakes
On a plate
If you don't have a cake board you can assemble a smash cake on a plate. I'll show you how to do it on a cake board next. Always start with a dot of buttercream in the middle of your plate or cake board. Push your first cake layer down onto it and it acts like glue to hold the cake in place. This way it won't slide around while you decorate it.
For the filling on this cake I'm using my 4 Minute Buttercream, adding melted chocolate chips to make it chocolate. You can use jam, caramel, Nutella, lemon curd… whatever you like. Using the back of a spoon, spread it so that it covers the cake up to the edges.
Flip your top layer upside down so that the part that was on the bottom of the cake pan faces upwards. This will give you the flattest top on your cake.
On a cake board
Making your cake on a cake board is the best option if you want smooth frosting. You'll also need a dot of buttercream to attach that first cake layer.
You can apply filling with a spoon or with an offset spatula. Spread it and make sure it's level so that your cake is straight and not leaning to one side.
After assembling your cake it's best to chill it in the fridge for about 30 minutes. This will mean fewer crumbs and less wobbling when you frost it.
How to frost smash cakes
The crumb coat
To prevent crumbs in your frosting, start with a thin layer called a crumb coat. This will trap any crumbs that come off the cake so that they don't get into your final layer. Use an offset spatula or palette knife to spread frosting over the top of the cake.
Then spread the frosting from side to side all the way from the top of the cake down to the bottom of the cake. The aim is to cover the whole cake so there is no cake (and no crumbs!) exposed. Hold your offset spatula against the side of the cake and spin your turntable to smooth the frosting. Don't worry about getting it perfectly smooth because you are going to cover up this layer.
Swipe sideways with your offset spatula to take off the uneven top edge of the frosting. Lift that frosting off with your offset spatula and scrape it back into your bowl. Swipe your offset spatula before each next swipe. Then chill the cake before doing the final coat.
After being in the fridge for about 30 minutes, the crumb coat will have set. This means it's firm instead of sticky. Now it's time for the final layer of frosting.
Frosting smash cakes without a cake comb
For the final layer of frosting I like to put frosting on the top of the cake first. Spread it all over the cake so that it sticks out over the sides, which will give you nice sharp angles later.
Spin the cake with your offset spatula at a 45 degree angle and that will level and smooth the frosting.
Then do the sides of the cake. You're aiming for two things here. First, you want to completely cover up the crumb coat so you don't see any of it. Secondly, you want to spread the frosting so that it's all about the same thickness. After covering the whole cake, if any of the frosting looks shallower or thinner, spread more over those areas.
Next you would typically use a cake comb to smooth the frosting. If you don't have one you can use a ruler! Press the base of the ruler down on the cake board to line it up straight against the cake. Then with your left hand or your non-dominant hand, start spinning the turntable as you push the ruler into the side of the frosting. Hold that ruler still as you spin the cake on the turntable so that the turntable is doing all of the work for you. When you've gone as far as you can, swipe the ruler off. Then use your offset spatula to scrape any frosting off the ruler so that it's clean and then repeat.
After scraping around the cake a few times you'll notice some indents or air pockets or gaps in the frosting. Use your offset spatula to scoop up some frosting and spread it over those indents and then scrape around again. Once your frosting is smooth, use your offset spatula to swipe sideways over the top edge of the cake.
After each swipe, scrape the frosting back into your bowl and wipe your offset spatula clean on a towel or paper towel. It needs to be perfectly clean before you swipe again. Now you have smooth sides on the cake and a sharp edge from the sides onto the top of the cake.
Frosting smash cakes with a cake comb
Now I want to show you how to smooth the frosting using a cake comb. Just like for the previous cake, I'm spreading the frosting to cover my cake. Then, instead of using a ruler I'm using a cake comb. Press the base of the cake comb down on the cake board and start spinning the turntable. The straight edge will take off all of the excess frosting, leaving a smooth layer behind.
After a few scrapes, touch up any imperfections by spreading more frosting onto those areas. Then scrape again and again until the frosting is smooth.
Side note: I used a tiny drop of gel colour to make this shade of pink. Gel colours are very concentrated so you only need a tiny amount to get really bright and bold colours.
If you don't have a cake comb, cake board or turntable you can use a plate and a spoon to decorate your cake. Spoon some frosting onto the top of the cake and spread it over the top just like you would with an offset spatula. It needs to cover the top surface and stick out over the edge of the cake.
Then scoop up more frosting and spread it around the sides of the cake. Don't worry about getting this neat at all at the moment. The only goal is to completely cover the cake with frosting.
The best way to get the frosting onto the cake is with little circular motions, which pushes the frosting onto the cake so it sticks without pulling off crumbs or chunks of cake with it when you swipe the spoon away.
When the cake is totally covered with frosting, use a paper towel or a towel wrapped around your finger to wipe around the edge of the cake. This takes any frosting smudges off the plate.
Now to tidy up this frosting dip your spoon into a cup of hot water, which will heat the metal. Create neat texture on the cake by moving your spoon in little arcs around the frosting. Because the metal of the spoon is hot it will smooth out the frosting as you do this, getting rid of any air pockets and leaving it silky and beautiful.
This frosting is definitely not smooth but the texture adds lots of detail and interest to the cake. If you want to make the frosting smooth without a turntable, try my turntable hack using a microwave!
Decorating smash cakes
Rustic textured frosting
You can create gorgeous rustic texture with your offset spatula or even a spoon. Push it gently into the frosting at the bottom of the cake and spin the cake. Your spoon or offset spatula will leave a groove in the cake. As you gradually drag it upwards, the grooves will continue upwards, creating this gorgeous texture all over the cake.
Whenever you notice frosting building up on your offset spatula or spoon, scrape off the excess into a bowl. Then continue up the cake. You can leave the top edge of the cake uneven for a rustic effect or you can level it to make it neater.
To add height to your cake, pipe some swirls on top. All you need for this is a star-shaped tip like a 1M tip.
Drop the piping tip into a piping bag. If you haven't used this piping bag before you'll need to cut it. Push the tip back a little bit, cut about halfway up where the tip was, and then push the tip back down.
Spoon a little bit of frosting into the piping bag. You don't need much so whatever is left in your bowl after frosting the cake is probably perfect! Squeeze the piping bag to push the frosting all the way down to the bottom. Twist the piping bag to push the buttercream down against the piping tip. This will mean you need hardly any pressure to squeeze the frosting out of the piping bag.
Hold the piping tip above your cake, squeeze the bag and pipe in circular motions. At the top of each swirl I like to push down slightly before releasing my pressure and then lift the bag up, which leaves a neat peak on the top of each swirl.
Sprinkle smash cakes
Finally, the easiest way to decorate a cake is with some sprinkles. It's best to do this just after frosting your cake, while the frosting is still soft and sticky so that the sprinkles stick to it. If you wait until the frosting sets, the sprinkles will bounce straight off the cake.
Serving smash cakes
Now it's time to serve your smash cake! You can slice these like any other cake for small portions, which is perfect for a small gathering.
Or dig into them with a fork, maybe for a couple's anniversary celebration. Or if you're following the smash cake trend, you give the cake to a baby on their first birthday and let them… smash it!
I hope this tutorial has been useful. Please ask me any questions you have in the comments and visit my cake school to learn hundreds of cake decorating techniques and designs.