Introduction: Easy Buttercream Birthday Cake!

About: Hi, I'm Asia of Cakes By Coffee, and I love cake decorating!!! I love it so much, that I spend a lot of time sharing my passion through teaching tons of cake decorating techniques to anyone who wants to learn.…

In this Instructable, I'll show you how to decorate a simple, yet very cute birthday cake once your cake is already baked. The following buttercream piping techniques are covered in detail: reverse shell, shell and star. A cookie cutter and sprinkles are also used to customize this cake design!


  • 2 layers of 8" round Cake- any flavor, cooled to room temperature and un-iced
  • Buttercream Icing- Approximately 4 cups (YouTube Video with Recipe)
  • Sprinkles
  • Metal or plastic cookie cutter
  • Cake leveler or serrated bread knife
  • 8" Cake Board
  • Flat dinner plate or cake base
  • Parchment paper
  • Disposable decorating bag
  • #21 Wilton Piping Tip
  • A pair of scissors
  • Cake turntable
  • Small metal spatula

Step 1: Step 1: Bake Your Cake

Start by making your favorite cake of choice from a box mix or from scratch. Be sure to follow the baking directions as indicated for your batter!

Step 2: Step 2: Prepare Your Cake for Decorating

After your cakes are baked, allow them to cool outside of the pan. Once the cakes are cooled to room temperature, remove any domed tops with a cake leveler or a serrated bread knife.

Step 3: Step 3: Ice Your Cake

Build your cake by alternating layers of buttercream icing and cake layers. To achieve nice, sharp cake edges, I would recommend icing your cake using the "upside down method". To see this method in action, check out this video. Once the cake is iced, place it onto the center of a flat dinner plate or cake base, and place it into the refrigerator for 15 minutes to set the icing. Remove the cake from the refrigerator and gently smooth the top of your cake further with your hand over a piece of parchment paper.

Step 4: Step 4: Prepare Your Decorating Bag

To prepare our decorating bag, place the number #21 Wilton tip into the disposable decorating bag. Next, note the location of the opening on the side of the tip, and score the bag slightly above these openings with the scissors. Next, push the tip away from the pointed end of the bag to reveal the score mark. Finally, cut the bag straight across the score mark with the scissors and push the tip into the new opening.

Step 5: Step 5: Fill the Decorating Bag With Icing

Next, fold the decorating bag down halfway and spoon the buttercream into the bag. Once the bag is about halfway full of icing, fold the sides of the bag back up. Finally, flatten and gather the piping bag.

Step 6: Step 6: Practice the Reverse Shell Technique

Holding the decorating bag at a 45-degree angle to the parchment paper surface with the top of the bag facing your body, gently squeeze the bag and form a backward question mark. Relax pressure on the bag to bring the reverse shell to completion. Follow the same steps for the next reverse shell, reversing the direction in which the previous shell was piped.

Step 7: Step 7: Practice the Shell Technique

Holding the decorating bag at the same 45 degree angle with the bag pointed toward your body, gently squeeze the bag while holding the tip down. Once the icing starts to bloom outward from the tip, relax pressure on the bag while pulling the tip down to complete the shell.

Step 8: Step 8: Practice the Star Technique

Holding the decorating bag completely vertical, touch the surface of the parchment paper with the piping tip. Squeeze gently while keeping the tip down. Finally, stop squeezing completely and then lift the decorating bag straight up to form a star.

Step 9: Step 9: Continue Practicing the Piping Techniques

Practice these piping techniques on parchment paper until you are happy with your results.

Step 10: Step 10: Pipe the Top Border Onto the Cake

Place your cake onto a turntable, and proceed to pipe reverse shells around the top edge of the cake to create a border.

Step 11: Step 11: Pipe the Bottom Border Onto the Cake

Next, pipe shells around the bottom edge of the cake to create a border.

Step 12: Step 12: Prepare Sprinkles

Next, pour sprinkles into a disposable decorating bag. Cut about 1 inch from the pointed end of the decorating bag. Doing this will give you better control of the sprinkles for the next step.

Step 13: Step 13: Center the Cutter on the Top of the Cake

Next, position the cutter on the top of the cake in the center. Gently press it into the buttercream icing and leave it in place.

Step 14: Step 14: Pour Sprinkles Into the Cutter

Next, pour the sprinkles into the cutter, filling the shape. Gently, press the sprinkles into the buttercream icing with a small metal spatula. Once complete, lift the cutter off of the cake.

At this point, you can leave the cake as is, but to embellish the top a bit more, proceed to the final step.

Step 15: Step 15: Add Stars Around the Sprinkles

To add a finishing touch, pipe a simple star border around the sprinkled number, letter or shape!