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Galaxy Mirror Glaze Cake: A Step-by-Step Guide

Galaxy Mirror Glaze Cake: A Step-by-Step Guide

Mirror glaze cakes have become extremely popular thanks to their incredible shine, bold colours, and the textures that can be created. The glaze is made from colouring white chocolate and sweetened condensed milk to give amazing, yet thin, coverage on buttercream cakes and frozen desserts. Here, I will show you step-by-step how to make a Galaxy Mirror Glaze Cake, prepared over my fat-free Skinnylicious cake with an all-natural strawberry Swiss meringue buttercream (as featured in my #1 bestselling book, “Have Your Cake and Eat It”).

This project was created and written by our baking mastermind, Mich Turner MBE.

Ingredients (for an 8″ cake to serve 16):


  • 6 medium eggs
  • 190g golden caster sugar
  • 190g plain flour (sieved)
  • 2 tsp vanilla bean paste


  • 225ml egg whites at room temperature (approx. 6 medium eggs)
  • 400g caster sugar
  • 3 tsp vanilla bean paste
  • 565g unsalted butter
  • 50g all natural strawberry powder (available from Squire’s Kitchen)


  • 20g gelatin powder (I used Dr Oetker)
  • 120g water (for the gelatin)
  • 280g liquid glucose (I used Dr Oetker)
  • 300g granulated sugar
  • 150g water
  • 200g sweetened condensed milk
  • 300g white chocolate
  • Food colouring – I used a selection from Wilton

Baking Tools & Decorating Accessories:

  • Three 8″ Sandwich Tins (loose bottom)
  • Large Cranked Handle Palette Knife
  • Small Cranked Handle Palette Knife
  • Wilton Mini Squeeze Bottles
  • Wilton Icing Colours:
    • White
    • Sky Blue
    • Royal Blue
    • Black
    • Rose
    • Violet
  • Paintbrush
  • Wilton Pearl Dust:
    • Black
    • Sapphire
  • Large Silver Cake Board to present
  • Wilton Decorate Smart Icing Smoother
  • 8″ Cake Board
  • Digital Thermometer
  • Stand Mixer (I used Kenwood K-Mix)

Read the Full (Printable!) Version of This Galaxy Mirror Glaze Tutorial Here!

METHOD: To Make the Cake

1. Preheat the oven to 160°C. Grease and line the base and sides of three 8″ round sandwich tins with non-stick baking paper.

2. In a large bowl, whisk the eggs with the caster sugar and the vanilla bean paste over a pan of barely simmering water just until the sugar dissolves and reaches a temperature of 40°C – 45°C (check with a thermometer or your fingers – it should feel like a hot bath).

3. Remove from the heat and transfer to an electric mixer. Continue to whisk at maximum speed for 15 minutes until the batter cools, thickens, and triples in size.

4. Add the flour 2 tablespoons at a time and gently fold in with a metal spoon or rubber spatula until fully combined. This will help to avoid lumps without overworking the sponge.

5. Transfer the batter to the prepared tins and bake in the oven for 25 – 30 minutes until risen, golden brown, and springs back when pressed.

6. Transfer to a wire cooling rack. Allow the cake to cool for 5 minutes, then turn it out and allow to cool completely.

METHOD: To Make the Swiss Meringue Buttercream

This Swiss meringue buttercream relies on heating together the sugar and egg whites to make a meringue, into which butter is beaten to thicken and stabilise it.

This buttercream has a wonderfully silky, velvety texture which is deliciously light. It handles beautifully for piping onto cupcakes and larger cakes and holds its shape well. Because the meringue is heat treated, this buttercream is stable at room temperature. I have flavoured and coloured this buttercream naturally with 100% strawberry powder.

1. Place the egg whites and the sugar in a large clean bowl over a pan of gently simmering water. Whisk with a hand balloon whisk and monitor the temperature with a thermometer until you reach 61°C – 70°C. This will take approximately 10 minutes.

2. Remove the meringue from the heat and attach the bowl to an electric whisk, but continue to whisk until the meringue cools to room temperature and has thickened.

3. Add the butter in small batches and beat well between each addition.

4. Add the vanilla and whisk until well combined.

5. Add the strawberry powder and continue to whisk until fully combined.

Note: The Kenwood K-Mix made light work of this and gave me a wonderfully light buttercream.

METHOD: To Frost the Cake

1. Place the first cake on an 8″ cake drum board. Use a palette knife to spread it generously with strawberry buttercream.

2. Place the next cake on top and repeat finishing with the third cake.

3. Spread the sides and top of the cake with strawberry buttercream and use a side scraper to level and smooth the sides of the cake. I used a small cranked handle palette knife to smooth the top. Place the cake on a larger work board and freeze overnight until it’s completely firm.

Top Tip: This buttercream recipe makes more than you will need — use the remainder to decorate cupcakes and serve these cakes with the larger cake. Store any unused buttercream in the fridge in an airtight container for up to 5 days.

METHOD: To Make the Glaze

1. Place the gelatin in a small bowl and pour the cold water over it. Stir and set aside to swell for 10 minutes.

2. Measure the sugar, water and glucose syrup together in a large saucepan, and bring to the boil up to a temperature of 103°C. Remove from the heat and whisk in the gelatin. Once combined, pour in the sweetened condensed milk and whisk until fully combined.

3. Place the white chocolate buttons into a large bowl and pour the hot sugar milk liquid over them. Allow to sit for 5 minutes to melt, then stir until fully blended and smooth. Use a stick/emersion blender to create a smooth liquid.

METHOD: To Colour & Apply the Mirror Glaze

1. Decant the glaze into smaller bowls and jugs, reserving the largest portion for the base colour. For the galaxy mirror glaze, I used navy and black to create the intense indigo colour. Colour each bowl with Wilton Icing Colour to reach the desired intensity.

2. Monitor the temperature – each glaze must be between 28°C – 30°C for optimum pouring. Too hot and the glaze will run off the cake; too cold and it will gloop and not flow easily. Transfer the pink and lilac glaze into small squeeze bottles for controlled application.

3. When you are ready to glaze, place the frozen cake on an upturned bowl over 2 sheets of cling film positioned at right angles over a lipped baking tray.

4. Mix the 2 blue colours together but do not stir. Pour liberally over the frozen cake to ensure the top and sides are covered, then move from side to side to create the streaks.

5. Swizzle the brighter pink and lilac colours across the top edge of the cake from the bottles in straight lines at subtle angles, and allow to settle.

6. Use a small palette knife to create a vortex whorl where the colours converge.

7. Use a paintbrush dipped in White Icing Colour to flick over the cake to create the stars.

8. Allow the glaze to settle and stop dripping for 15 minutes. Use a sharp knife to remove the drips from the base of the cake and then lift the cake carefully onto a presentation cake board. Allow the glaze to firm and the cake to come up to room temperate before serving.

Find the Printable Version of This Galaxy Mirror Glaze Tutorial Here!

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