How to Ice & Decorate a Train-Themed Number Cake

If you’re planning a birthday cake shaped like a “3,” this fun train theme is a guaranteed hit 🎉Before we start: I won’t get into the cake baking here—this guide is all about decorating. If you don’t want to carve the shape yourself, you can use a ready-made number cake pan like this one:

Number 3 cake pan:

https://www.amazon.com/s?k=number+3+cake+panOnce your cake is baked, cooled, and ready, let’s turn it into a train adventure!

What You’ll Need

Buttercream frosting (store-bought or homemade)

Decorations

Oreo sicks, Chocolate frosting or melted chocolate (for “tracks”)Toy train cars (cleaned well before use)Birthday candles

Cake board or serving platter (upgrade from foil!)Paper towels (for cleanup)Small spoon or ziplock bag (for piping chocolate)

Food Coloring:
https://www.amazon.com/s?k=gel+food+coloring

Offset spatula:
https://www.amazon.com/s?k=offset+spatula

Piping bags:
https://www.amazon.com/s?k=piping+bags

Toy train set:
https://www.amazon.com/s?k=toy+train+set

Step 1: Color Your Frosting

Mix your buttercream with a few drops of gel food coloring until you get a soft minty green.💡 Tip: Gel coloring gives you vibrant color without thinning your frosting.

Step 2: Frost the Cake

Place your number 3 cake on a platter or cake board.Spread frosting over the entire surface.Keep it slightly textured—this adds to the playful look. Tip: A thicker layer helps smooth out edges and gives that soft, fluffy finish.

Step 3: Build the Tracks

Arrange oreos along the curves of the “3” like railroad ties.Pipe chocolate frosting or drizzle melted chocolate to connect them. This simple step really sells the train-track effect!

Step 4: Add the Train

Place toy train cars along the track.Follow the curve of the cake for a dynamic look.Make sure everything is stable and evenly spaced. Safety tip: Wash and dry toys thoroughly before placing them on the cake.

Step 5: Add Candles

Insert candles into the train cars or directly into the cake. Use matching colors for a coordinated look—or mix it up for fun.

Optional Finishing Touches

Crushed Oreos for a “gravel” effectGreen sprinkles for grass. Extra frosting details like bushes or borders.