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

No special pans. No carving skills required. Just a simple rectangular baking dish and a few simple tools are all you'll need to create this cake cutie.

Make a sweet & simple onesie cake!

Bonus: Tint the cake batter the pink or blue, then decorate in gender-neutral colors to turn this treat into a gender reveal cake!


  • Rectangular cake
  • Small knife
  • Buttercream
  • Sprinkles
  • 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 the cake cracked a bit, but not to worry! Buttercream will come to the rescue!

Step 2

Cut a half circle from the middle of one of the short ends of the cake for 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 curved, not straight across.

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!

Step 4

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

Place a piece of parchment paper on top of the cake and gently run your hands over it to set the sprinkles in the buttercream. You'll get a smooth surface perfect for piping.

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

Step 6

Personalize your onesie by adding a name or special message.

August 09, 2018
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How to Make the Easiest (and Cutest!) Baby Shower Cake