A colouring book cake is an entertaining activity and it can also be calming and therapeutic! This is a fun project for kids and adults alike.
How to prepare a colouring book cake
The frosting on your cake needs to be very firm so that you don't damage it as you colour. After you've smoothed the frosting, put the cake into the fridge for a few hours or even overnight. This will chill it so that the frosting sets. I'm using my 4 Minute Buttercream for this cake (and all of my cakes!) but any crusting buttercream will work.
Find a picture you'd like to create on your cake or draw one to refer to. Or just go freestyle straight onto the cake if you're feeling confident! I like to use melted semi-sweet chocolate chips for drawing onto cakes. The chocolate gets firm when it sets so you won't damage it later as you colour. Melt them in the microwave for 30 seconds at a time using 50% power so that the chocolate doesn't burn or seize. Stir until any lumps of chocolate have melted and the chocolate is smooth. Then spoon the chocolate into a sandwich bag and push it down to one of the bottom corners.
I know in some countries Ziploc bags are harder to find or more expensive than piping bags. If that's the case, you can use a piping bag instead. Cut a tiny piece off the corner of the sandwich bag or the end of the piping bag.
Now outline your design, which can be just on top of the cake or around the sides as well. Piping with chocolate is easier than with buttercream because chocolate flows so easily through the hole in the bag. You could choose a theme like a Christmas scene for your kids to colour during the holidays or whatever else they're interested in! Pause at each corner before piping the next line so that the chocolate pools and attaches to the cake. If you pull away too soon you'll pull the chocolate with you and leave rounded corners instead of sharp ones.
Adjust or tidy up the chocolate by nudging it with a toothpick straight away, while the chocolate is still soft. You can scrape off any mistakes without damaging the frosting, since it has been chilled and the buttercream has set.
It's much trickier to pipe onto the sides of the cake than the top for two reasons. First, because you can't see as well what you're doing! And second, because gravity pulls the chocolate down so unless you keep the tip of the piping bag pressed against the cake, your chocolate lines will fall down to the cake board.
If your lines are too thick you won't be able to pipe smaller details. If that happens, push the melted chocolate to the other corner of the sandwich bag. Now cut a smaller piece off of this corner so that your lines will be thinner. Even for small details you'll need space inside the shape so that you'll have something to colour in later.
After piping the design, put the cake back in the fridge for about 30 minutes to set the chocolate.
Prepare your colours
While the cake is in the fridge, prepare your colours. There are a few options for this. You can can buy edible markers but they don't work as well on buttercream as they do on fondant. The ink doesn't work for very long, I think because of the oiliness from the butter in the buttercream. Also, if you press too hard you'll poke through the firm outer layer of the buttercream. The soft buttercream underneath will cover up the tip of the pen and it won't work anymore.
You can use piping gel, which you can buy from cake decorating supply shops in lots of colours. Or, if you want a quick option that you can make yourself, just use your buttercream colours! You can make a colour palette in a cupcake pan or mini cupcake pan or use a few bowls. I like to use a cupcake pan because it's much quicker to wash than lots of little bowls.
I drew the colours I was going to use and taped them to the cupcake pan because I wasn't sure how easily you'd be able to see the colours in the pan.
Squeeze a drop of liquid or gel colour into each cavity of the pan. To dilute the paint to make it easier to paint with, you'll need to add a clear liquid. Gels tend to clump in water so instead, add a few drops of clear alcohol like vodka or a clear flavour extract. I'm using peppermint extract for my Christmas colouring book cake.
If you're you're not going to use your colours immediately, cover the pan with plastic wrap so that the liquid doesn't evaporate.
Colouring book cake activity
When you take your cake out of the fridge, the frosting and chocolate will stay firm for about 30 minutes. This gives you lots of time to colour in the design. Using a different paintbrush for each colour is ideal but if you don't have that many paintbrushes, keep a glass of water and a towel or paper towel handy to clean the paintbrush after each colour. The smaller and thinner the brushes, the better, so that you can reach into the small parts of the design.
This is a fun activity for children but also a very calming, therapeutic activity for anyone! I persuaded my husband to test it out with me as a date night activity and we really enjoyed it. And if you want to do this activity with kids but don't have much prep time, skip the chocolate outline! Let them paint straight onto the cake to make their own masterpiece.
I hope you've enjoyed this tutorial! Tell me in the comments who you're going to make this with or for! For more cake decorating ideas and courses and memberships visit my online cake school 🙂