Cake Decorating Blog

How to Make the Easiest (and Cutest!) Baby Shower Cake Ever

You’d never believe how easy this adorable onesie cake is. No special pans. No carving skills required. Just a classic, rectangular baking dish and a few simple tools are all you’ll need to create this cake cutie.

Make a sweet & simple onesie cake!

Onesie Cake | Erin Gardner | Craftsy

Bonus tip: Looking for a creative take on a gender reveal cake? Tint the cake batter the correct color before baking and finish the cake in gender-neutral tones.


  • Rectangular cake
  • Small knife
  • Buttercream (this recipe is a good choice)
  • Star sprinkles (or ones that match your event)
  • Parchment paper
  • Small round piping tip
  • Piping bag

Step 1:

Trim the top of your cake flat and flip it onto a platter. I baked my cake in a 15″ x 10″ glass baking dish, but the technique will work with any rectangular cake. A tiny bit of my cake stuck to the bottom of the pan and I have a little crack from flipping it out. Not to worry! Buttercream will come to the rescue!

Rectangular cake | Erin Gardner | Craftsy

Step 2:

Cut a half circle from the middle of one of the short ends of the cake. This will be the onesie’s neck hole.

Then, cut the corners off the opposite end of the cake to make the onesie’s leg holes. Make your cuts slightly arched, not straight across.

Trimming the cake | Erin Gardner | Craftsy

Step 3:

Discard (or nibble on) the neck cut-out, but save the leg cut-outs to make the onesie’s sleeves. Trim the arched sides of the corners so they’re flat. Place the cut edges against the sides of the cake, lining the corners up with the top edge of the cake. You now have your onesie’s shape!

Placing the sleeves | Erin Gardner | Craftsy

Step 4:

Ice the cake with buttercream frosting and coat the freshly iced surface with a layer of sprinkles. I used bright star sprinkles, but you can use any color or shape of sprinkles you like.

Iced onesie | Erin Gardner | CraftsyOnesie with sprinkles | Erin Gardner | Craftsy

Then, place a piece of parchment paper on top of the cake. Run your hands over the paper, gently pressing the sprinkles into the buttercream. Doing this will give you a smooth, even surface to pipe the onesie’s details.

Smoothing out the sprinkles | Erin Gardner | Craftsy

Step 5:

Fill a piping bag fitted with a small round tip with buttercream. Pipe a few details onto the surface of your cake:

  • Outline the onesie
  • Embellish the neck and sleeves with additional lines
  • Add a curved line and dots for snaps at the bottom of the onesie
Piped details | Erin Gardner | Craftsy

Step 6:

Personalize your onesie by adding a name or special message.

Finished onesie cake | Erin Gardner | Craftsy

How easy was that? You’ll definitely want to keep this idea on hand. Save this tutorial to Pinterest so you can find it later!

Easy Onesie Cake

FREE Guide! Not-So-Basic Buttercream Decorating Ideas

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Get insider tricks & inspiration to make one-of-a-kind buttercream goodies in this FREE PDF guide, available exclusively on Craftsy.Get My FREE Guide »


Annie Trabal

Looks simple and cute. Iam looking for ideas for fondant babies shoes, cna anyone help me

Erin Gardner

Hi Annie! Craftsy has a wonderful fondant baby shoes class taught by the fabulous Sharon Wee. Seriously the cutest fondant baby shoes I’ve ever seen! Here’s a discounted link for the class:


The free fondant tutorial also explores baby shoes. Fiddly but looks easy enough. Try downloading the tutorial. It might take a long time to download so be patient!


This looks soo cute and simple! One question, how do you ice the sides where the leg/neck holes are cut without the cake crumbling? I always have this problem! Hoping to make it for my SIL’s baby shower tomorrow!

Erin Gardner

Hi! If you chill your cake before you ice it, then there are typically less crumbs. You might also try doing a crumb coat first, chill the cake, and then finish the cake with a thicker coat of frosting. Thanks!

Elaine Marten

putting it right in the freezer to freeze will also stop crumbs from falling, and I found with cakes like this if you ‘glue’ the shoulder bits, etc, with icing that helps them stick in place while you ice the whole thing. Another thing, for booties/shoes. I have made them with marshmallows. One for the back (heel to top of the bootie) and the other one, joined by toothpicks, on its side as the foot/toe part, then ice them with whatever kind of icing patterns you want…rosettes, twists, etc…really easy and you can make them before and just let them dry. You can also make them from the large or regular size marshmallow pending on what size you would want for the cake, or even some table decorations


Thanks for sharing will definitely make for my boy for his first bday


Would you use two cake mixes?

Erin G

That’s a good question! I typically bake from scratch, so I don’t know for certain. My best guess would be yes if you’re using the same size pan as I did. I think one box of mix would bake up too short. Sorry I couldn’t offer more help! If anyone else knows, please feel free to chime in. 🙂


Can you use just regular cake icing to ice this type of cake or does it have to be a certain kind? Please help! Thanks!!

Erin G

Hi! I used American buttercream to finish this cake, but you can use whatever you like! It really doesn’t matter. Thanks 🙂


Thank you Erin I’m going to attempt to do regular vanilla icing.

Anita Hodgins

thank you so much for posting this! I am excited to give it a try! 🙂


Thinking of doing a test run for a baby shower coming up. Could you tell me where the neck part is placed at on the cake?

Erin Gardner

Hi! The neck cutout does not make a return to the cake. Consider it the baker’s reward! 🙂


I made this dorm my son mad daughter in law’s shower and it is adorable!! Thanks so much for the wonderful idea.


I’m so excited to try this for a baby shower next week! Thanks so much for the walk-through!!!!


Has anyone made this with box cake mix? Did you use one or two boxes?


I used a box mix and only needed one box for a 9×13 pan


Which cake did you bake? Do you have a recipe?


What cake did you bake? Do you habe a recipe?


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