If you are a beginner baker, and need a birthday cake for your Lego lover, here is the perfect solution.  A Lego birthday cake that uses no fondant and a box cake mix.

Not only is it easy to make, it is easy to customize too. This cake can be made in different colors, with different size bricks…whatever you like.

You Will Need

Now let’s put it together.

Step 1 – Preparation

Preheat oven to 350F (180C).  Grease cake pan with baking spray or butter.

Step 2 – Bake Cake

Mix the cake ingredients together – box mix, butter, eggs and water – for 2 minutes on low speed.  The mixture should be smooth and evenly colored.  Pour into prepared pan and bake for 40 minutes.

Test to make sure the cake is done – it should spring back when touched gently in the centre.  Or an inserted skewer should come out clean.

Once ready, set it aside to cool completely.  If you are running short on time, pop it in the fridge to cool.

Step 3 – Prepare Frosting

While your cake is baking, color the frosting.  Spoon into bowls – one for each color.

Add food coloring and mix well.  Start with a few drops and if you want the color darker, mix in more.

Step 4 – Level Cake and Cut

Nice straight edges are important for Lego, so you need to level the cake.  This will give it a nice flat top.

Use a cake leveler for best results.  But if you don’t have one, use a sharp bread knife and steady hand!

Take it nice and steady and cut through the cake, removing the top.

Now cut the cake into equal thirds using a sharp cutting knife.  Cut one of the thirds in half so you end up with 4 bricks.

Step 5 – Crumb Coat

The cake has been cut up a lot and all of the sides are exposed.  This creates a lot of crumbs, so you’ll want to apply a ‘crumb coat’ which makes the final or second layer of icing a lot smoother.  See how to do it here.

To do the crumb coat, choose one brick and 1 color of frosting.  Apply 1 coat of frosting on all 4 sides and the top.  Don’t worry if this coating is a bit messy and not perfect.  Another layer is going to be added so you won’t see it.

Once done, put the iced brick in the fridge for about 20 minutes. Repeat this with the other bricks and colors.

Step 6 – Decorate

Time to add the marshmallows so the cakes become lego bricks.

Using your kitchen scissors, cut the marshmallows in half.  To make sure they don’t stick, spray the scissors with a bit of baking spray before hand.

Dip the marshmallow into the frosting (if it is a bit thick, pop it in the microwave for a few seconds first) and pull it out.   You can do this with your fingers or a spatula.  Make sure the marshmallow is evenly coated.

Place the coated marshmallow on top of the brick.  Repeat until you have all your Lego lumps in place.  Make 8 lumps for the big bricks, and 4 for the smaller ones.

Step 7 – Serve

Position the finished Lego bricks on a plate or cake board ready to serve.  For extra decoration you could place some Lego pieces or figurines around the cake.

Now it’s time to light the candles and enjoy the cake.


For a great tutorial on how to make a Lego birthday cake, check out this video by Nerdy Nummies on Youtube or watch it below.