Mirror Glaze Galaxy Cake

I’m a huge lover of NASA, space, and all things astronomy. And SpaceX is no different. The SpaceX Falcon 9 launch in May 2020 was one of the most exciting launches I’ve seen in a long time, and was an event that instilled some hope in humanity while this world is still getting over a pandemic and many other large global events. I wanted to make a cake to celebrate the launch, and what better than to make a galaxy-themed mirror glaze mousse cake? And of course, I made it matcha because I just love matcha everything.

This recipe involves several components: sponge base, matcha mousse, and mirror glaze. They all take some time to make and set, but it’ll all be worth it in the end!

I’d also like to give a shoutout for GirlStyle Singapore for featuring my mirror glaze recipe! This was before I had a blog to host my recipes, so big thanks to them for writing up my recipe.

Tips:

• A springform pan is highly recommended for mousse cakes, since extracting them from the pan can be a very delicate process. The removable bottom makes it easy to take the cake out.
• I recommend splitting the process over 2 days. There is are a lot of components and waiting involved, and it’s best to not rush the process! You can make the sponge cake and mousse in one day, and prepare the mirror glaze and assembly for the next day.

Print Recipe

Matcha Galaxy Mirror Cake Recipe

Recreate the galaxy in your kitchen! This recipe can be made for a 6 – 9in (15 – 22cm) diameter cake. Expect to have some leftover sponge cake depending on how you assemble the cake.

Ingredients

Matcha Sponge Cake

• 2 large eggs room temperature
• 50 g flour
• 7 g matcha powder
• 60 g granulated sugar
• 25 g butter melted
• 20 ml milk warm
• 2 tsp water

Matcha Mousse

• 1 tbsp gelatin powder
• 4 tbsp water cold
• 2 large egg yolks
• 1/2 cup sugar
• 1 cup milk
• 1 cup heavy cream
• 1 tbsp matcha powder
• 3 tbsp water warm

Mirror Glaze

• 21 g gelatin powder
• 1 cup water
• 300 g granulated sugar 1 1/2 cup
• 200 g sweetened condensed milk 1 cup
• 340 g white chocolate 1 1/2 cup
• gel food coloring Royal blue, light blue, purple, pink, white

Instructions

Matcha Sponge Cake

• Sift matcha powder and flour 2-3 times until there are no large clumps
• Line a cake tin with parchment paper and preheat oven to 350°F/170℃.
• Using a hand mixer on high speed, whisk eggs and sugar in a bowl over another bowl of water at around 140°F/60℃
• Once the temperature of the eggs reach around 96°C/36℃, remove from warm water and continue whisking until the mixture is thick and creamy, about 5 minutes. Lower the speed and whisk for 3 more minutes until glossy.
• Add 1 tbsp water and whisk lightly to loosen the batter.
• Gently fold in matcha and flour mixture until smooth, then fold butter and milk to the mixture until creamy.
• Pour mixture into lined cake pan and bake for 20-25 minutes, or until inserting a toothpick into the center comes out clean. If there is still batter stuck to the toothpick, bake for 5 more minutes but watch the cake carefully.
• Once removing from the oven, quickly drop the pan from a 8in/20cm height to shock the cake and prevent shrinking.
• Turn upside down onto a rack and let cool. Once fully cooled, cover and place in fridge to chill for 2 hours. In the meantime, prepare the mousse.

Matcha Mousse

• In a small bowl, whisk gelatin and 4 tbsp cold water and set aside until the gelatin absorbs the water and solidifies. In a separate bowl, whisk egg yolks and sugar.
• In a small pan, heat the milk on medium-low and dissolve the gelatin mixture into the milk. Slowly add the milk to the egg and sugar mixture and set aside.
• In a small bowl, dissolve matcha in the warm water and add to the gelatin mixture. Whisk thoroughly while cooling the bowl in ice water.
• In a large bowl, whisk heavy cream until medium peaks form. Carefully fold the whipped heavy cream into the matcha mixture, taking care not to overmix.
• Remove the sponge cake from the fridge and carefully remove it from the pan. The sponge cake will be the base for the mousse. Depending on how tall you want your cake to be, cut at least 1 in/2.5 cm through the bottom of the cake with a serrated knife.
• With a springform pan or a cake pan, put the base sponge layer on the bottom, and fill the rest of the pan with mousse. Work quickly on this step before the mousse sets. Chill in fridge for several hours until the mousse is set.
• Mirror Glaze
• Whisk gelatin and 1/2 of the cold water in a bowl and set aside until the gelatin absorbs the water and solidifies.
• In a small saucepan over medium heat, combine the remaining 1/2 cup water, sugar, and condensed milk. Stir until mixture dissolves and bring to a simmer. Remove from heat and add the solidified gelatin and whisk until dissolved.
• Add white chocolate and let the remaining heat soften the chocolate for several minutes. Whisk slowly until smooth.
• Divide the glaze into separate bowls, each containing a different color. One bowl should be a larger portion to contain a base color (royal blue or sky blue), while the smaller bowls will contain accent colors (purple, pink, white).
• Whisk a few drops of food coloring into its designated bowl. Let the glaze cool down until 90°F/32°C, or until it barely feels warm when touched. (This is very important!) Stir frequently to prevent it from settling.

Assembly

• Remove the mousse cake from the fridge and carefully remove it from the pan. Place it over a covered baking tray with aluminum foil for easy cleanup.
• In a new bowl, pour about 1/3 of the base glaze and add some accent glaze drizzles on top. Use a chopstick or spoon to give it a few swirls for a galaxy effect. Then, pour this combined glaze over the cake until the top and sides are fully covered. Drip with a spoon a few lines of the accent colors on top of the cake.
• Add edible sprinkles, glitter, or accents to complete the look.
• Let the cake rest for about 15 minutes until the glaze is set, then transfer to the fridge if saving for later. It can be eaten either chilled or at room temperature.

Notes

Recipe by Usagi Baking. All images and content belong to me unless otherwise specified. Please do not use my images without permission. If you would like to share my recipe, please credit me and link back to my site.