The Babysitters Club + The Momofuku Birthday Cake

For the birthday cake soak
55g milk
1 teaspoon (clear) vanilla extract

Make the birthday cake crumb
1. Preheat the oven to 150°C and line a rimmed baking tray with baking paper.
2. Combine the sugars, flour, baking powder, salt and sprinkles in the bowl of a stand mixer fitted with a paddle attachment. Mix on low speed until well combined. Add the oil and vanilla and mix on low speed until small clumps form.
3. Spread the clumps on the prepared baking tray. Bake for 20 minutes, breaking up the clumps once or twice during baking.  The crumbs should be slightly moist to the touch; they will dry and harden as they continue cooling. Allow the crumbs to cool completely before using.
The crumbs can be stored in an airtight container at room temperature for 1 week, or in the fridge or freezer for up to 1 month. 

Make the birthday cake
1. Preheat oven to 180°C and line a 9×13″ baking tray with baking paper.
2. In a measuring cup, combine the buttermilk, grapeseed oil, and vanilla extract.
3. In a medium bowl, whisk together the flour, baking powder, salt, and 1/4c of the sprinkles.
4. Combine the butter, shortening, and sugars in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium-high for 2-3 minutes. Scrape down the sides of the bowl, add the eggs, and mix on medium-high for 2-3 minutes. Scrape down the sides of the bowl once more.
5. On low speed, gradually pour in the buttermilk mixture. Gradually increase the mixer speed to medium-high and beat for 4-6 minutes, until the mixture has nearly doubled in size and is completely homogenous (don’t rush this step!) Stop the mixer and scrape down the sides of the bowl.
6. On low speed, gradually add the flour mixture and mix just until the batter comes together, about 45-60 seconds. Scrape down the sides of the bowl and give the batter a final mix with a rubber spatula.
7. Spread the cake batter in an even layer in the prepared pan. Sprinkle the remaining 2 tablespoons of sprinkles evenly on top of the batter. Bake the cake for 30-35 minutes; when you gently poke the edge of the cake with your finger, the cake should bounce back slightly, and the center should no longer be jiggly. Place the pan on a wire rack to cool completely.
The cake can be stored in the fridge, wrapped in plastic wrap, for up to 5 days.

Make the birthday cake frosting
1. In a small bowl, whisk together the glucose, corn syrup, and vanilla extract.
2. Combine the butter, shortening and cream cheese in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium-high for 2-3 minutes, until the mixture is smooth and fluffy. Scrape down the sides of the bowl.
3. With the mixer on its lowest speed, stream in the glucose mixture. Increase the speed to medium-high and beat for 2-3 minutes, until the mixture is silky smooth and glossy. Scrape down the sides of the bowl.
4. Add the powdered sugar, salt, baking powder and citric acid, and mix on low speed just to incorporate them into the batter. Increase the speed to medium-high and beat for 2-3 minutes, until the frosting is completely smooth.
Use the frosting immediately, or store in an airtight container in the fridge for up to 1 week.
*Bring to room temperature before using in the recipe*

Assembling the birthday cake in all its glory
1. Put a piece of baking paper on the bench. Invert the cake onto it and peel off the baking paper from the bottom of the cake. Use the cake ring to stamp out 2 circles from the cake. These are your 2 top layers. The remaining cake bits will come together to make the bottom layer of the cake.
2. Layer 1 – the bottom: Clean the cake ring and place it in the center of a baking tray lined with clean baking paper. Use 1 strip of acetate to line the inside of the cake ring.
3. Put the cake scraps in the ring and use the back of your hand to tamp them down into an even flat layer.

4. In a small bowl, whisk together the milk and vanilla extract for the birthday cake soak. Using a pastry brush, brush half of the soak over the top of the cake.
5. Using the back of a spoon, spread 1/5 of the frosting in an even layer over the cake.

6. Sprinkle 1/3 of the birthday cake crumbs evenly over the top of the frosting, use the back of your hand to press them gently into the frosting.
7. Use the back of a spoon to spread another 1/5 of the frosting as evenly as possible over the crumbs.
8. Layer 2 – the middle: With your index finger, gently tuck the second strip of acetate between the cake ring and the top 1/4 inch of the first strip of acetate, so that you have a clear ring of acetate 5-6 inches tall. Set one of the cake rounds (the more imperfect of the two) on top of the frosting, brush with the remaining soak, and repeat the process for Layer 1 (a 1/5 of the frosting, 1/3 of the crumbs, another 1/5 of the frosting).
9. Layer 3 – the top: Nestle the remaining cake round into the frosting. Cover the top of your cake with the last 1/5 of the frosting. Garnish the frosting with the remaining birthday cake crumbs.

10. Transfer the baking tray to the freezer and freeze for a minimum of 12 hours to set the cake and filling. (The cake will keep in the freezer for up to 2 weeks.)
11. At least 3 hours before you are ready to serve the cake, pull the baking tray out of the freezer and, using your fingers and thumbs, pop the cake out of the cake ring. Gently peel off the acetate and transfer the cake to a platter or cake stand. Let it defrost in the fridge for a minimum of 3 hours before slicing and serving. (You can store the cake, wrapped in plastic, in the fridge for up to 5 days.)

Notes

• Make sure the baking tray you are using to assemble your cake actually fits in your freezer!
• Canola oil can be substituted for the grapeseed oil.
• The glucose is used to keep the frosting smooth, give it body and meld the ingredients together. An additional 2 teaspoons of corn syrup can be substituted for the glucose in the frosting.
• Here in NZ, corn syrup is not commonly found. To be honest, I thought glucose and corn syrup were the same thing. I used all glucose in the frosting, and while I don’t have anything to compare it to, it turned out great.
• The citric acid is used to enhance the flavour and cut the sweetness of the frosting. I don’t recommend leaving it out.
• Christina calls for clear vanilla extract because of the distinct flavour it imparts (more common in US bakeries). It’s not found in NZ supermarkets but you can buy it from specialist cake decorating shops. I used normal vanilla extract.
• I had a lot of trouble finding acetate strips within driving distance. You can order them online from some online cake decorating shops, I found mine at Miss Bon Bon’s. They are a bit thinner so I ended up using 3 strips.
• I used a 6.5″ Gobel ring mould that I found at Milly’s Kitchen.

© Once Upon An Egg. All images and content are copyright protected. Please don’t use my images without permission. If you want to republish this recipe, please re-write it in your own words, or link back to this post for the recipe.