Number Shaped LEGO Cake

We have been seeing tons of number shaped cakes lately and I knew that I wanted to try it for our next collective kid’s birthday. Harrison has a February birthday, so he was first up. Which is perfect, because I knew his expectations would be really low and approving of my mediocre baking skills.

Number 7 shaped lego cake

It also worked out that he was turning 7, which seemed like a pretty straight forward number to make with it’s straight lines.

Here is my disclaimer: this is an extremely amateur production. The perfectionist in me cringes every time I look at it, but I’m not a professional baker and the birthday boy loved it, so that’s enough. This tutorial is meant for all the moms on a budget trying to make their kid’s birthday dreams come true. It’s also meant to give major credit to bakers who create masterpiece cakes, because this is hard!

I chose to use box cake mix, as opposed to making it from scratch like I usually prefer. I knew the emphasis for this cake would be on the design rather than a specific flavor. Cake mix usually comes out pretty uniform and dense, which was exactly what I needed to build this cake.

I baked two boxes in 9×13 glass Pyrex dishes. Then, I flipped it out onto a cutting board (make sure to spray the dish really well and wait until the cake cools for best results), then used another cutting board to flip it right side up.

Next, use a serrated knife to cut out the number you want. I removed the edges first because I was going for crisp, clean edges, rather than the crispier baked edges.

The unfrosted sheet cake I started with to make the number cake. You will want to use a serrated knife.

Repeat this step with the second cake to create the second layer. Of course, you could use only one cake if you wanted the number to be smaller.

Once the number cake is cut out, arrange it on a platter or serving tray. I used a piece of foam board wrapped in wrapping paper.

The unfrosted cake cut into a number 7 and ready to be frosted.

I had to get a little creative when arranging my number cake because I decided I didn’t like how I cut the first layer and changed it. This meant I had to use some scraps to arrange it how I wanted it. I used toothpicks to hold pieces in place until I frosted.

Once the cake is how you want it to look, start frosting. The frosting will basically act like glue to hold all the pieces in place. Since you have cut edges, the frosting will get crumby. The easiest way to fix this is to do a very thin crumb layer. This doesn’t have to be pretty, it’s mostly just to get everything in place and keep the crumbs from spreading as you decorate.

The number cake with a crumb layer before decorating.

Once your crumb layer is in place, put the cake in the fridge for at least 30 minutes. This allows the frosting to stiffen up and “glue” the crumbs in place. Now you can frost over and you should not have any crumbs.

To make my number cake LEGO themed, I frosted Oreos to put on top. Holding them and frosting them entirely was tricky, so I used a piping bag to try and fill in the gaps.

The number cake frosted and almost finished. I used Oreos to make it look like a LEGO.

I also piped around the border where the cake met the board to cover up all the messy parts. Then, I used a fine tip to pipe “LEGO” on each button/knob/round thing (what are those called?!).

The finished number LEGO cake!
Close up of LEGO number cake.

Not bad, if you stand 20 feet away, or are in constant motion like a 7 year old! I think this would look really good with fondant, but I am not that skilled.

One tip while frosting- if you get too many “pointy” sections where you’d rather it be flatter, dip your finger in cornstarch and tap the frosting down. The cornstarch will fade away and it prevents the frosting from sticking to your finger so you can smooth it out. That trick saved me with this one!

Do you usually make your kid’s birthday cake or buy them?

You can see more kids’ birthday parties!

Isla’s Unicorn Rainbow party // Sullivan’s Modern Pirate party // Nolan’s Banana Bash // Isla’s mermaid party // Harrison’s pizza party

What do you think? Leave a comment!