Milk Bar’s 30 day baking challenge has been a fun challenge. Christinia Tosi takes you step by step on how to build every delicious recipe she includes in this series. After spending hours on her videos, she becomes your friend on the screen and I’ll miss her!

Ingredients for Birthday Cake Soak

(makes 60 g or 1/4 cup)

55 g whole milk (1/4 cup)
4 g clear vanilla extract (1 tsp)

Ingredients for Birthday Cake Crumb

(makes 275 g or 2 1/4 cups)

100 g granulated sugar (1/2 cup)
25 g light brown sugar (1 1/2 Tbsp, tightly packed)
90 g cake flour (3/4 cup)
2 g baking powder (1/2 tsp)
2 g kosher salt (1/2 tsp)
20 g rainbow sprinkles (2 Tbsp)
40 g grape seed oil (1/4 cup, can substitute with vegetable or canola oil) 12 g clear vanilla extract (1 Tbsp)

Ingredients for Birthday Cake Sponge

(makes 1 quarter sheet pan)

55 g unsalted butter, at room temperature (4 Tbsp or 1/2 stick) 60 g vegetable shortening (1/3 cup)
250 g granulated sugar (1 1/4 cups)
50 g light brown sugar (3 Tbsp, tightly packed)

3 eggs
65 g grape seed oil (1/3 cup, can substitute with vegetable or canola oil) 110 g buttermilk (1/2 cup)
8 g clear vanilla extract (2 tsp)
245 g cake flour (2 cups)
6 g baking powder (1 1/2 tsp)
3 g kosher salt (3/4 tsp)
50 g rainbow sprinkles for batter (1/4 cup)
25 g rainbow sprinkles for sprinkling on cake (2 Tbsp)

Ingredients for Birthday Cake Frosting

(makes 430 g or 2 cups)

115 g unsalted butter, at room temperature (8 Tbsp or 1 stick) 50 g vegetable shortening (1/4 cup)
55 g cream cheese, at room temperature (1/4 cup or 2 oz)
25 g glucose (1 Tbsp)

18 g light corn syrup (1 Tbsp)
12 g clear vanilla extract (1 Tbsp)
200 g confectioners’ sugar (1 1/4 cups) 2 g kosher salt (1/2 tsp)
0.25 g baking powder (a pinch)
0.25 g citric acid (a pinch)

Ingredients for layer cake assembly

(makes 1 cake)

1 recipe Birthday Cake Soak
1 recipe Birthday Cake Crumb 1 recipe Birthday Cake Sponge 1 recipe Birthday Cake Frosting

Materials

Stand mixer + paddle attachment
Kitchen scale
Small and medium bowls and containers
Rubber spatula
2 quarter sheet pans
Parchment paper
Non-stick cooking spray
6-inch cake ring
5- or 6-inch tall acetate strips (or 3- to 4-inch; tape two pieces together for 5-6 inches) Chef's knife
Gem scale (optional)
Oven thermometer (optional)
8-inch cardboard round (optional)

115 g unsalted butter, at room temperature (8 Tbsp or 1 stick) 50 g vegetable shortening (1/4 cup)

55 g cream cheese, at room temperature (1/4 cup or 2 oz)

25 g glucose (1 Tbsp)

18 g light corn syrup (1 Tbsp)

12 g clear vanilla extract (1 Tbsp)

200 g confectioners’ sugar (1 1/4 cups) 2 g kosher salt (1/2 tsp)

0.25 g baking powder (a pinch)

0.25 g citric acid (a pinch)

Ingredients for layer cake assembly (makes 1 cake)

1 recipe Birthday Cake Soak

1 recipe Birthday Cake Crumb 1 recipe Birthday Cake Sponge 1 recipe Birthday Cake Frosting

What to do:

Make the Birthday Cake Soak

(5 minutes)

1. Swirl or mix the milk and vanilla together in a small container or bowl. Set aside.

Make the Birthday Crumb (30 minutes)

1. Preheat the oven to 300°F (150°C).

If you have an oven thermometer, check to make sure that your oven is at the correct temperature.

2. Combine the sugars, cake flour, baking powder, salt, and rainbow sprinkles in the bowl of a stand mixer fitted with the paddle attachment, and mix on low speed until well combined.

You can gauge when your ingredients are mixed based on the distribution of sprinkles throughout the mixture.

3. Combine the oil and vanilla in a small container or bowl and mix them together. Then with your mixer on low speed, stream the oil and vanilla in as close to the middle of the bowl as possible.

The wet ingredients will act as glue to help the dry ingredients form small clusters, so continue paddling until these clusters appear. The largest crumbs should be no larger than a half-inch in diameter.

Check the bottom of the bowl for any lingering dry ingredients and fold them in with a spatula.

4. Pour the crumb out onto a quarter sheet pan lined with parchment. Use your fingertips to spread the crumb out evenly.

5. Bake for 20 minutes, then check to make sure they are browning very slightly. The crumbs should contract just a bit to form individual boulder shapes when they're done—if they haven't yet, leave them in the oven for another two or three minutes.

If you plan on baking your cake sponge immediately afterward, you can clean up your space and start preparing the sponge recipe as the crumb bakes.

6. Let the crumb cool completely before using in a recipe. Stored in an airtight container, the crumb will keep fresh for 1 week at room temperature or 1 month in the fridge or freezer.

Bake the Birthday Cake Sponge

(45 minutes)

1. Preheat the oven to 350°F (175°C).

2. 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, just until it all comes together. Scrape down the sides of the bowl.

3. Crack the eggs into a small container. Add the eggs to the mixture one at a time with your mixer on low speed, making sure each is fully incorporated before adding the next. After you add each egg, you can increase the speed to high for a few seconds to help the ingredients incorporate.

4. Mix on high for 2-3 minutes. Scrape down the sides of the bowl once more, looking for any streaks of ingredients that haven't been incorporated.

When it's done, the mixture should be light tan, glossy, and homogenous. If it looks like the ingredients are still distinct and trying to separate, cream for another 2-3 minutes. It's okay to see some sugar granules in the mixture.

5. On low speed, stream in the grape seed oil toward the center of the bowl and then switch to high speed and paddle for 3-6 minutes until the mixture is practically white, twice the size of the original fluffy butter-and-sugar mixture, and completely homogenous.

6. Turn down your mixer to low speed and stream in the buttermilk and vanilla just a little at a time until fully incorporated.

7. Combine the cake flour, baking powder, salt, and 50g rainbow sprinkles in a medium container or bowl and mix with a spoon. Add the dry ingredients into your mixing bowl. On the lowest mixer speed, mix for 45 to 60 seconds, just until the dry ingredients are well distributed.

Scrape down the sides and bottom of the bowl thoroughly to ensure the batter is fully mixed. If not, keep lightly working the batter with your spatula until any dry ingredients are fully incorporated.

8. Spray a quarter sheet pan with baking spray in an 'X', line it with parchment, and spray the top of the parchment and the sides of your pan.

9. Pour the batter into the prepared quarter sheet pan and, using a spatula, knife, or the back of a spoon, spread the cake batter in an even layer.

10.Sprinkle the remaining 25 g rainbow sprinkles evenly on top of the batter.

11. Bake the cake for 30 minutes, checking intermittently for uneven browning. The cake will rise and puff, doubling in size.

At 15 minutes, take a look at the cake with your oven light to see if any areas are browning more than others. If so, very gently rotate the cake in the oven (intense movement can cause your cake to deflate). For the next 15 minutes, you can check on the cake with the oven door closed every 5-10 minutes and rotate if you see uneven browning.

If you notice the cake is getting too much color on top but isn't set in the center yet, you can reduce the oven temperature to 325°F until the cake is baked through.

At 30 minutes, use your finger to gently poke around the outside and center of the cake. It should bounce back very slightly and not be jiggly at all. Leave the cake in the oven for an extra 3-5 minutes if it doesn’t pass these tests.

12. When baked through, remove the cake from the oven and allow to cool to room temperature. The cooled cake can be stored in the fridge wrapped in plastic wrap for up to 5 days.

Checkpoint 2: You can pause here if you'd rather continue later today or tomorrow.

Make the Birthday Cake Frosting (15 minutes)

1. Combine the butter, shortening, and cream cheese in the bowl of a stand mixer fitted with the paddle attachment and cream together on high for 2-3 minutes until the mixture is smooth and fluffy. Scrape down the sides of the bowl.

2. Add the glucose, corn syrup, and clear vanilla extract and paddle on low speed until fully incorporated. Crank the mixer up to high and beat for about a minute until the mixture is silky smooth, glossy, and white. Scrape down the sides of the bowl.

Pro Tip: Spray a spoon and small container with cooking spray to help measure your glucose so it doesn't stick too much.

3. Combine the confectioners’ sugar, salt, baking powder, and citric acid in a container or bowl and add to the stand mixer bowl. Start on low, then crank the speed up to high and mix for 3 minutes or until you have a stark white, beautifully smooth and fluffy frosting. It should look just like it came out of a plastic tub at the grocery store!

Use the frosting immediately, or store it in an airtight container in the fridge for up to 1 week.

Checkpoint 3: You can pause here if you'd rather continue later today or tomorrow.

Birthday Layer Cake Assembly

(30 minutes + 3 hours of freezer time)

1. Lay out all of the components of your cake:

1 recipe Birthday Cake Soak

1 recipe Birthday Cake Crumb 1 recipe Birthday Cake Sponge 1 recipe Birthday Cake Frosting

2. Place your cooled sponge on the counter and, using a sharp paring knife, the back of a spoon, or a bench scraper, loosen the cake from the sides of the sheet pan.

3. Place a piece of parchment or a baking mat on the counter and invert the cake onto it, giving the far edge of your overturned pan a sharp rap on the counter to release the cake (refer to the video to see how Christina does it). Peel off the parchment stuck to the cake and discard it.

4. Use your cake ring to stamp out 2 circles from the cake, one from the upper right-hand corner and one from the lower left-hand corner (or lower right-hand and upper left-hand corners), which will form the top and middle layer of the cake. Refer to the video to see how Christina does this.

Make sure to plan out your circles to make sure you know exactly where to stamp before completing this step — you can mark them lightly on your sponge using your cake ring.

Use the ring to stamp out two half-circles from the remaining sponge, which will come together to make the bottom layer of the cake.

5. Clean the cake ring and place it on the 8-inch cardboard round, or any other cake board, platter, or parchment-lined pan.

6. Use 1 strip of 5-6" tall acetate to line the inside of the cake ring. If your acetate strips are shorter than 5 inches, you can add a second one once your cake is built up high enough (we'll tell you when to do this below).

7. Place the two half circles of cake together inside the ring, spongey (not browned) side up, and fill the gap between them with additional pieces of cake scrap. Use the back of your fingers to press the scraps together into a flat, even layer.

8. Using a spoon or a pastry brush, splash or brush half the soak over the bottom layer of cake.

9. Spread one fifth of the frosting in an even layer over the cake using the back of a small spoon that fits into the acetate collar, or a spoon you've bent into a ladle-like shape.

Use figure-8 motions and try to not pick up your spoon as you work.

10. Sprinklesmallerpiecesofcrumbmakingupathirdofthetotalcrumbevenlyoverthefrosting. You'll want to save the bigger pieces of crumb for the top of the cake. Anchor the crumbs into place in the frosting using the back of your fingers.

11. Use the back of a spoon to spread another fifth of the birthday cake frosting as evenly as possible over the crumb. You should see some crumb peeking through the frosting.

12. Place your middle cake layer on top of the frosting, passing it through the acetate collar at an angle to help it nestle into place.

If one of the two cake rounds left looks nicer, save it for the final layer and use the other one in the middle.

If you're using two shorter pieces of acetate, you can now add your second piece. Gently tuck a second strip of acetate between the cake ring and the top of the first strip of acetate, so that you have an acetate collar that is 5-6" inches tall.

13. Addsomecrumbscrapsalongtheedgesofyourcakeifyouseeanygapsorareaswherefrosting is coming up and press down with your fingers.

14. Repeat the process of splashing or brushing the layer with the remaining soak, spreading it with one fifth of the frosting, sprinkling one third of the crumb (still reserving the biggest ones for the top), and finishing with another fifth of the frosting.

15. Nestle the remaining cake round onto the frosting. Cover the top of the cake with the remaining frosting and add any desired visual effects like spikes, swirls, or a flat surface using a spoon, knife, or offset spatula.

16. Garnish the frosting with the remaining crumb or rainbow sprinkles.

17. Transfer the cake to the freezer and freeze for a minimum of 3hours (or overnight) to sett he cake and filling. The cake will keep in the freezer for up to 2 weeks.

18. At least 3 hours before you are ready to serve the cake, pull the cake out of the freezer and slide off the cake ring. If you need to, use your fingers and thumbs to pop the cake out of the ring.

19. Gently peel off the acetate and transfer the cake to a platter or cake stand, or whatever you want to serve it on. Let it defrost for 2-3 hours. Wrapped well in plastic, the cake can be refrigerated for up to 5 days.

20. When the cake is fully thawed, slice and serve to lucky friends and family!

Sprinkle Birthday Layer Cake-Milk Bar