Making a square cake can be tricky but these six hacks will make it easier!
#1 You don't need a square cake pan
First, if you don't have a square cake pan don't run out and buy one! Save the money and bake a rectangular or sheet cake instead, assuming you already have one of those pans. Cut it into squares and stack them to make a layer cake. This 9x13 inch Very Vanilla sheet will make a tall 4 inch square cake:
You'll have some narrow extra pieces at the edge of the cake. Glue these together with a bit of buttercream to make an extra layer. This way you'll use up all of the cake you baked and make a taller cake.
#2 Make your square cake pan non-stick
To bake a square or rectangular cake that doesn't stick to the pan, line the pan with parchment paper. Cut a piece the size of the pan plus whatever the height of the pan is. This pan is 2 inches high so I'm adding 2 inches on each side of the pan.
Cut a slit about that same height - 2 inches for this pan - into each edge of the paper.
Unless you make square cakes regularly you probably won't have square cake boards. Instead of buying them just for this, use a round cake board instead. Choose one that's at least 4 inches wider than the cake.
For this 6 inch square cake I'm using a 10 inch round board. The extra inches will give you space to frost and decorate your cake without buying any new cake boards.
#4 Chill your cake layers
I think the most important hack for square cakes is to chill the cake before frosting it. After 30 minutes in the fridge, cake gets cold and firm so it won't crumble as you spread buttercream onto it. I use this 4 Minute Buttercream for all of my cakes! Cold cake holds its shape so you'll create straight sides around it. Room temperature cakes are much more delicate so as you spread on your frosting you can pull off chunks, which makes it more difficult to get a neat square shape with your frosting.
#5 Don't skip the crumb coat
If you've made several cakes before you'll definitely know that a crumb coat is essential for preventing any crumbs getting into your final layer of frosting. Definitely don't skip the crumb coat! When the crumb coat sets, which takes about 15 or 30 minutes in the fridge, any crumbs that came off the cake will be stuck into it so they won't get into the final layer of frosting.
#6 How to frost a square cake
My hack for sharp angles on a square cake is a simple cardboard box. Cut out a square of cardboard that's half an inch bigger than the cake. Wrap this in parchment paper to make it food safe and non-stick.
Now spread frosting onto the top of the cake only. Push the wrapped cardboard square down onto it, adjusting it so it's centered on the cake.
Next, spread frosting around the sides of the cake. It needs to be at least as thick as the edges of the cardboard square. When you smooth the frosting, your cake comb will scrape along the edge of the cardboard, making the frosting mimic the perfectly straight edges and sharp angles of the cardboard square.
Put the cake in the freezer for 15 minutes or the fridge for 30 minutes to set the frosting. Then slice underneath the parchment with a knife to lift up the wrapped cardboard square.
Spread more frosting over the top to fill in any gaps, scrape off the excess and voila!