Making a themed birthday cake doesn’t have to be hard. Sometimes you just have to think outside the box when picking your design. Many LEGO cake ideas involve either round cakes to simulate minifigure heads or lots of fondant to create bricks.
Easy LEGO birthday idea
Instead of making a cake with lots of LEGO bricks, I decided to make a LEGO cake that was just one extra large LEGO brick. A cake with a lot of detail could be a very frustrating endeavor. So I went simple and big with one giant LEGO brick.
LEGO Cake Recipe
Start by baking your cake in a 1-lb loaf pan. Use your favorite homemade cake recipe or keep it easy and buy a box of cake mix – Don’t worry I won’t tell! 🙂
I let the cake cool briefly before dumping it out of the pan. But like most cake recipes, I recommend cooling the cake completely before frosting it.
LEGO Birthday Cake
Now you could totally try and make the LEGO studs out of fondant but why when marshmallows are way easier to use! For this cake, cutting standard marshmallows in half worked well to create the appropriate size for the LEGO studs to place on top of the brick.
Use food coloring to create whatever LEGO brick color you want. This is a fun way to theme this cake to any LEGO party theme. For example, making pink or purple frosting would work great for a LEGO Friends birthday party.
Frosting the LEGO Brick
I have boys so we kept it to a simple blue frosting. Now you could simply frost the cake and marshmallows with buttercream frosting at this point. That’s what we did the first time I made this cake. It’s a little messy and it wasn’t as smooth looking as I wanted.
The next time I made the cake, I warmed up the frosting first and poured it over the cake. This created a much smoother LEGO brick cake.
- Cake Mix
- 4 Marshmallows
- Grease a 1-lb loaf pan before pouring cake batter in. Use a box of cake mix or your favorite homemade recipe.
- Follow cake directions for baking and allow to cool slightly before removing cake from pan by turning it upside down. Allow it to cool completely before decorating it.
- Cut 4 marshmallows in half and arrange them on top of the cake like a LEGO brick. The cut side of the marshmallows will be slightly sticky, helping it stick to the top of the cake.
- Place the cake on a wire rack on top of a large cutting board or cookie sheet.
- Warm the frosting up in the microwave until it's smooth and stirs easily. I suggest stirring after 30 second intervals to check consistency.
- Pour frosting over the top of the cake. Scrape up the excess underneath and reheat it to pour again if necessary. Use a spatula to cover any places that are a little thin on frosting.
Don't overheat the frosting. You want it runny enough to pour over the cake but not too hot. Let it cool down before pouring if it's too hot.
LEGO-themed birthday party
To make it extra special, display it on a LEGO base plate and add a few Minifigures. I suggest placing a piece of parchment paper under the cake to keep things cleaner.
Are you for LEGO birthday party ideas? I have a post dedicated to easy LEGO party ideas include decorations, activities, and party favors. I hope it helps you plan an easy and fun lego-themed birthday party.
More LEGO Birthday Cakes
Don’t love my LEGO birthday cake idea? Don’t miss these other LEGO cakes and other LEGO dessert ideas that would be great for a LEGO birthday party.
Want to forgo a traditional birthday cake for your LEGO party? How about adorable LEGO cake pops? If you are looking for yummy and AMAZINGLY easy then LEGO brownies or LEGO Batman cookies are perfect.