The Momofuku Birthday Cake
Author: 
Serves: 12-18
 
Makes one 18-cm/7-inch cake. You’ll have leftover cake scraps, enough to make four of these cute Mini Birthday Cakes!
Ingredients
For 3 18-cm/7-inch cake layers you need to bake a sheet cake and a round cake:
For the quarter sheet pan (25x38-cm or 10x15-inch):
  • 245g (or 2 cups – 2 teaspoons) cake flour
  • 6g (or 1½ teaspoons) baking powder
  • 3g (or ½ teaspoon) table salt
  • 50g (or ¼ cup) rainbow sprinkles for the batter
  • 55g (or 3 tablespoons + 2¾ teaspoons) unsalted butter, softened at room temperature
  • 60g (or ⅓ cup) vegetable shortening
  • 250g (or 1¼ cup) granulated sugar
  • 50g (or 3 tablespoons + 2 teaspoons, packed) light brown sugar
  • 3 large eggs (or 168g)
  • 110g (or ½ cup – 2 teaspoons) buttermilk
  • 65g (or ⅓ cup) grapeseed oil
  • 8g (or 2 teaspoons) clear vanilla extract
  • 25g (or 2 tablespoons) rainbow sprinkles for sprinkling
For the round cake pan:
  • 78g (or ½ cup + 2 tablespoons) cake flour
  • 1.9g (or ½ teaspoon) baking powder
  • 1g (or a big pinch) table salt
  • 16g (or 4 teaspoons) rainbow sprinkles, for the batter
  • 18g (about 4 teaspoons) unsalted butter, softened at room temperature
  • 19g (or 5 teaspoons) vegetable shortening
  • 80g (or ⅓ cup + 1 tablespoon) granulated sugar
  • 16g (or 1 tablespoon + ½ teaspoon) light brown sugar, packed
  • 53g whole egg (almost 1 large egg)
  • 35g (or 2 tablespoons + 1 teaspoon) buttermilk
  • 21g (or 5 teaspoons) grapeseed oil
  • 2.5g (or ½ teaspoon) clear vanilla extract
  • 8g (or 2 teaspoons) rainbow sprinkles for sprinkling
For the crumble:
  • 140g (or ½ cup + 3 tablespoons + ½ teaspoon)granulated sugar
  • 35g (or 2 tablespoons + 1½ teaspoon, packed) light brown sugar
  • 125g (or 1 cup) all-purpose flour*
  • 2.8g (or ½ teaspoon + 1 pinch) baking powder
  • 2.8g (or ½ teaspoon – 1 pinch) table salt
  • 28g (or 2 tablespoons + 2½ teaspoons) rainbow sprinkles
  • 56g (or ⅓ cup + 1 teaspoon) grapeseed oil
  • 16g (or 1 tablespoon) clear vanilla extract
For the frosting:
  • 190g (or ¾ cup + 4 teaspoons) unsalted butter, softened at room temperature
  • 85g (or ½ cup – 1½ teaspoons) vegetable shortening
  • 95g (or 3.3 ounces) cream cheese, softened at room temperature
  • 68g (or 2 tablespoons + 2 teaspoons) glucose**
  • 20g (4 teaspoons) clear vanilla extract
  • 335g (or 2½ cups + 3 tablespoons) powdered sugar
  • 3g (or ½ teaspoon) table salt
  • pinch of baking powder
  • scant ¼ teaspoon lemon juice
For the soak:
  • 80g (or ⅓ cup) whole milk
  • 1 teaspoon clear vanilla extract
Instructions
Start with the sheet cake:
  1. Preheat oven to 175°C/350°F (standard oven setting). Butter a 25x38-cm (10x15-inch) rectangular sheet pan and line the bottom and long sides with baking parchment. Set aside.
  2. In a medium-sized bowl, whisk together flour, baking powder, salt and sprinkles for the batter.
  3. In the bowl of a stand mixer fitted with the paddle attachment, combine butter, shortening, granulated sugar and light brown sugar. Mix on high speed for 2-3 minutes.
  4. Crack the eggs in a bowl and scramble with a fork to break the yolks and mix it with the white. Add the egg in four additions, beating well after each addition.
  5. Combine buttermilk, oil, and vanilla in a large glass. Turn mixer to low and stream in the buttermilk mixture. Increase mixer to high and beat for 4-6 minutes until mixture is light and fluffy. Scrape the bowl with a rubber spatula every now and then.
  6. Add the flour mixture and fold it into the batter with a rubber spatula until mostly incorporated. Mix on low for 10-20 seconds.
  7. Pour batter into the prepared pan, spreading it in an even layer with the back of a spoon. Sprinkle with the sprinkles reserved for sprinkling.
  8. Bake on a rack in the middle of the oven for 23-28 minutes, or until a tester inserted into the center of the cake comes out clean.
  9. Remove from oven and allow to cool completely before turning out.
  10. Cooled cake can be stored in the fridge for up to five days, wrapped tightly in plastic wrap.
Make the round cake:
  1. Preheat oven to 175°C/350°F (standard oven setting). Butter a 20-cm (8-inch) round cake pan and line the bottom baking parchment. Set aside.
  2. Make the batter according to the instructions for the rectangular sheet pan, but use a handheld mixer instead of a stand mixer.
  3. Bake on a rack in the middle of the oven for 18-20 minutes, or until a tester inserted into the center of the cake comes out clean.
  4. Remove from oven and allow to cool completely before turning out.
  5. Cooled cake can be stored in the fridge for up to five days, wrapped tightly in plastic wrap.
Make the crumble:
  1. Preheat oven to 150°C/300°F (standard oven setting) and line a cookie sheet with baking parchment. Set aside.
  2. Combine granulated sugar, light brown sugar, flour, baking powder, salt, and sprinkles in a medium bowl. Add oil and vanilla, and using your hands, mix until no dry spots remain and large clumps form when mixture is pressed together. Break the dough up into clusters (some small, some large) and spread onto prepared baking sheet.
  3. Bake in the middle of the oven, stirring occasionally with a wooden spoon, until the crumble is light golden brown and crunchy, 10–12 minutes (it will firm up as it cools).
  4. Remove from the oven and let cool completely.
  5. Crumbs can be stored in an airtight container at room temperature for five days.
Make the frosting:
  1. Combine butter, shortening, and cream cheese in the bowl of a stand mixer fitted with the paddle attachment and mix on high speed for 2-3 minutes, or until light and fluffy. Scrape the sides of the bowl with a rubber spatula if necessary.
  2. Add the glucose, corn syrup, and vanilla and mix again on high speed for 2-3 minutes, or until the frosting looks glossy white.
  3. Add powdered sugar, salt, baking powder, and lemon juice and, using your spatula, mix until just combined. Mix on high speed for 4-6 minutes, until the frosting is beautifully white and fluffy.
  4. Frosting keeps, stored in an airtight container in the fridge, up to 1 week.
Make the soak:
  1. Combine milk and vanilla in a small pouring jug and stir to combine.
Assemble the cake:
  1. Invert cakes onto clean board/counter and peel off baking parchment. Using an 18-cm/7-inch springform pan collar as a guide, cut 2 rounds out of the sheet cake and 1 out of the round cake using a paring knife. Save the scraps to make those cute mini cakes!
  2. Get yourself a serving platter and check whether it fits in your freezer. If it fits, place an 18-cm/7-inch springform collar (or a cake ring) in the center. Line the inside of the springform collar with acetate (my acetate came in 10-cm/3-inch strips, so I used two separate strips to line the pan).
  3. Place one of the cake rounds in the springform pan, pressing it down to the serving plate. Carefully drizzle the cake layer with half of the soak. Use the back of a spoon to spread one third of the frosting evenly over the cake. Sprinkle one fourth of the birthday crumbs evenly over frosting and press the crumbs into the frosting with the back of a spoon.
  4. Top with the second cake round. If your acetate comes in thin strips, gently tuck the second acetate strip between cake ring and the top cm/¼-inch of the first acetate strip now, so that you have a clear ring of acetate 5–6" tall—high enough to support the height of the finished cake.
  5. Drizzle the second cake layer with the remaining milk mixture and frost with half of the remaining frosting. Scatter one third of the remaining crumbs over the frosting and press them into the frosting with the back of a spoon. Place the remaining cake round on top.
  6. Cover top of cake with remaining frosting. Top with remaining birthday crumbs.
  7. Transfer cake to freezer and freeze at least 12 hours to set cake and filling. The cake will keep in the freezer for up to 2 weeks.
  8. At least 3 hours before serving the cake, pull sheet pan out of freezer and remove the springform collar. Gently peel off acetate strips. Defrost in fridge or on the counter for at least 3 hours, but preferably longer. Serve cold or at room temperature.
Notes
* the original crumble recipe calls for cake flour, but I was all out and all-purpose flour works fine, too.
** I only use glucose, because it’s basically the same thing as corn syrup.
Recipe by The Tough Cookie at https://thetoughcookie.com/2017/04/05/momofuku-birthday-cake/