Strawberry Milkshake Birthday Cake Recipe

This Strawberry Milkshake Birthday Cake is delicious and easily adaptable for any shaped cake. The sweet pink icing is flavored with an ingredient you probably already have in the cupboard to give it the authentic milkshake taste.

Little Baker (LB) is thankfully still very much in the easy to please stage. Just before her 4th birthday, I asked her what she wanted to for her birthday cake. The reply was a pink number four cake topped with some of her favorite things – biscuits, marshmallows and chocolate. This is how the strawberry milkshake birthday cake was born. Just a bit different from her monkey banana cake request from last year. I was just thankful the reply didn’t feature a My Little Pony or Moana.

Her 4th birthday was also the first time she’s had a proper little party with nursery friends so I decided to make the main cake for blowing out candles with accompanying cupcakes for the kids to take home to save the faff of cake cutting at the end of the party.

We’ll ignore the fact that we nearly forgot to cut the cake at the party. Kid’s birthday parties are stressful for the parents especially when there are parents there from Nursery you don’t really know and in a way want to impress.

I made the cake using a 9-inch square tin and baked it in one go. To make things easier you could bake in a smaller tin and/or bake the layers separately. The method for making the number 4 will still be the same no matter the size of the square cake you start with.

The extra fun for this cake was that it was baked and decorated during the 2018 heatwave. Never before have I been so glad that I wasn’t working with sugar paste or chocolate. The decorated cake lived in the fridge until it came to serving.

How To Make The Perfect Buttercream

I’ve tried many buttercream recipes over the years and always go back to the tips Holly Bell taught me.

  • Always use salted butter as it helps take the sweetness away from the sugar.
  • Use the ratio one part butter, 2 parts icing sugar.
  • Use an electric food mixer and beat for 7 mins. This will give you lovely white, fluffy buttercream.
  • Color the buttercream with food color paste rather than liquid. I particularly like Sugar flair paste.

How do I make number-shaped birthday cakes?

This is when I confess Pinterest is your friend. This is the post I’ve used for the last few years. Some numbers are easier than others, but all are created from simple round, square or rectangular tins that you most likely already have at home. No need to buy a new expensive shaped tin.

You can see how I made a number 1 for LB’s rabbit birthday cake.

Can I make banana milkshake icing instead?

You can flavor the icing however you want. Leave it simply vanilla or try other milkshake powders like banana or different flavorings that takes your fancy.

Top tip: don’t try milkshake syrups like the new sugar-free version of Crusha. It is more like a cordial than syrup and doesn’t flavor the icing well.

Top Tips:

  • Don’t rush making the cake. You can make the sponge in advance and freeze (without the filling)
  • You can also make the buttercream in advance too. Put the buttercream in an airtight container in the fridge for up to two weeks. Allow the buttercream to come to room temperature before spreading on the cake.
  • The advantage of this cake is that there are lots of discards. Enjoy the “chef perks”, freeze the offcuts for later or make some easy cake truffles.

Strawberry Milkshake Birthday Cake Recipe

No fancy tin required, just a square tin and a sharp knife.

The method for making the number four will work with any size square cake. You can also top with any biscuits or sweets that take your fancy.

Prep Time: 15 mins
Cook Time: 1 hr 15 mins
Decorating Time: 1 hr
Total Time: 1 hr 30 mins
Course: Dessert
Keyword: Birthday cake
Servings: 16 people
Author: Jules



  • 360 g butter softened
  • 360 g caster sugar
  • 6 eggs large
  • 360 g self raising flour
  • 1 tbsp vanilla extract
  • 1-2 tbsp semi skimmed milk
  • 200 g raspberry jam

Strawberry milkshake buttercream:

  • 250 unsalted butter softened
  • 500 g icing sugar sifted
  • 2 tbsp strawberry milkshake powder
  • 1 tbsp semi skimmed milk
  • pink or red food colouring gel optional


  • Selection of biscuits and sweets


  • First make the cake. In a large bowl beat together the butter and sugar until light and fluffy.
  • Mix in the eggs one at a time. If the mixture begins to look curdled, add a spoonful of flour.
  • Add 1-2 tbsp. of milk until the cake mixture is of dropping consistency then pour into a 9 inch square baking tin lined with baking parchment.
  • Bake in a preheated oven at 160°c for 60-75 minutes until the cake is cooked through. If the cake begins to brown too much on the top before cooked through place a piece of foil on the top of the cake.
  • Once baked remove from the oven and allow to cool in the tin for 10 minutes before turning out on to a wire rack top side down, remove baking paper and allow to cool completely.
  • While cake is cooling make your buttercream. Put your butter in your mixer and beat until light at fluffy. Gradually beat in the icing sugar a 1/3 at a time to help stop coating your kitchen in icing sugar.
  • When all the icing sugar has been added finally beat in the milkshake powder and milk. Continue to beat for two more minutes. If you want the icing to be more pink add a tiny amount of food coloring gel.
  • When cake is completely cool level off if needed with a knife then split in half so you have two layers.
  • Spread the jam over the bottom layer then place the other layer on top. Cut your cake in to three equal pieces.
  • The easiest way to construct the 4 is to make a paper template first. Cut a square the same size as your cake then split this piece of paper in to three. Label them 1, 2 & 3.
  • Piece number 1 will be the horizontal part of the 4. You can leave this piece alone, hurrah!
  • Piece number 2 is the vertical part of of the 4. Cut the bottom 1/6 off. This will be the foot of the number, let’s call it A.
  • For piece number 3 you have two options. Get all mathematical or use a cheat/winging it method. I went for the latter. Position 1, 2 and A to form the horizontal and vertical sides of number 4. Take 3 and place it so the top long edge touches top left corner of 1 and top left corner of 2. Using a pencil draw lines where you need to cut, then cut these away and discard. You now have your stencil.
  • Place these stencils on to your three pieces of cake and cut cake to size. Discard (or eat) any surplus cake. Don’t throw away the templates yet.
  • Secure the pieces of cake in the shape of a 4 on to your cake board with a small amount of icing.
  • Using a palette knife coat all sides of the cake with a thin layer of buttercream. Don’t worry if you can see some of the cake through it. Then put cake in the fridge to cool. This is your crumb coat layer that will help keep the crumbs away from your final layer of icing.
  • While your crumb coat is setting layout your leftover templates in the 4 shape and this this to plan where you’re going to place your sweets and biscuits as the topping.
  • Coat the cake with the remaining buttercream then place the biscuits and sweets on the top.

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