I’m going to be upfront about it: this cake is involved. Like, A. Project. But if you don’t mind a project for a special occasion, say, your youngest’s second birthday, well then, you’re in for a real treat! The upside is that it can be broken down into steps and made ahead of time and kept in the freezer until the morning of the day you need it, at which point you transfer it into the fridge until the party. I made a lactose-free version of it and it was AH-ma-zing. Like seriously, possibly the best birthday cake you can conjure up. That being said, the road there wasn’t exactly smooth.
To refresh your memory, Christina Tosi is the chef at Momofuku Milk Bar (she’s the one who invented cereal milk ice cream and crack pie, too). I really got into this cake when I saw her on Chef’s Table, Season 4, Episode 1. (Admitedly, some found it lacking. While we’re at it, here’s an interview focused on how she stays so thin even though she’s a famous pastry chef.) The recipe for her birthday layer cake is in her cookbook, but I referred to the version published in Bon Appétit. Which, as it turns out, is erroneous: when I baked the cake in the specified 9”x13” jelly roll pan, which I had bought specifically for the occasion, it overflowed and I had a disaster on my hands. There’s nothing in the comments about this, but a bit of googling revealed I wasn’t the only one. I think that the problem stems from the fact that Christina Tosi calls for a quarter sheet pan (assuming this is the original recipe in her book), and then Bon Appétit went on to quantify those measurements as 9”x13”. The problem is that a quarter sheet pan IS NOT A STANDARD MEASUREMENT! So let me save you some trouble here: what you want is a rimmed baking sheet (such as a jelly roll pan) measuring 10”x15”. Smaller and your cake batter will overflow; bigger and your cake will be too thin and burn. For the record, there’s a pretty big difference in volume between a 9”x13” pan and a 10”x15” pan, so I’m surprised Bon Appétit let that slide! In any event, I had to make the cake a second time, and it turns out that the 9”x13” pan wasn’t a complete waste because that was the only size that would fit in my lower-drawer freezer for the last step! Plus, the Fox loves playing with it now.
My version (below) is lactose-free! It all works with Earth Balance sticks, even the frosting. It’s also nut-free as long as your ingredients aren’t cross-contaminated (I’m thinking of the sprinkles and clear vanilla extract in particular).
Before you even attempt this, make sure you have all the ingredients and equipment: in addition to the 10”x15” pan, you’ll want a roll of 3”-wide acetate and some clear vanilla extract (I bought Wilton, but Christina Tosi recommends McCormick). The distinctive imitation taste of the clear vanilla extract really makes this cake. You also need either a 6” cake ring or a 6” springform mold (I have the latter). The resulting cake is small, obviously, but it was enough for 4 adults and 2 kids. Also, as per the recommendations on Liv for Cake (which had solved the pan size issue), I made 1.5 times the recommended amount of frosting – you’ll have a bit leftover, but that way at least you won’t run out, and that’s what I wrote below. Since this recipe is so involved, it’s a good idea to start at least several days ahead of time, so that you can course-correct if needed.
All that being said, this was an amazing cake. The crumb is a vanilla funfetti that tastes like the best version you remember from childhood (even for me who hadn’t had those types of cakes on my birthday!), the crumbs are almost like a funfetti granola, and dang it if that frosting isn’t the best one I’ve ever had! I’m making that frosting again for sure; it was stark white, had the perfect consistency, and wasn’t too sweet (although the finished, assembled cake certainly was). I think we all really loved it. The Little Prince has even asked me to make it again for his birthday – oy! I’d actually love to adapt it to make a regular 2-layer, 8- or 9-inch round cake. Do let me know if any of you have tried!
For the cake
2 cups cake flour
1 ½ tsp. baking powder
¾ tsp. kosher salt
¼ cup + 2 Tbsp. rainbow sprinkles, divided
1 ½ tsp. vinegar + enough lactose-free milk to make ½ cup (instead of ½ cup buttermilk)
1/3 cup grapeseed oil
2 tsp. clear imitation vanilla extract
1 ¼ cups granulated sugar
1/3 cup vegetable shortening
4 Tbsp. (½ stick) lactose-free butter or margarine, at room temperature
3 Tbsp. light brown sugar
3 large eggs
For the crumbs
¾ cup cake flour (or all-purpose flour)
½ cup granulated sugar
2 Tbsp. light brown sugar
2 Tbsp. rainbow sprinkles
½ tsp. baking powder
½ tsp. kosher salt
¼ cup grapeseed oil
1 Tbsp. clear imitation vanilla extract
For the frosting and assembly
¾ cup (1 ½ sticks) lactose-free butter or vegan margarine, at room temperature
6 Tbsp. vegetable shortening
3 oz. lactose-free cream cheese, at room temperature
3 Tbsp. light corn syrup
1 ½ Tbsp. + 1 tsp. clear imitation vanilla extract, divided
7.5 oz. powdered sugar
¾ tsp. kosher salt
3/8 tsp. baking powder
¾ tsp. fresh lemon juice
¼ cup lactose-free milk
For the cake
Preheat oven to 350 °F. Line a 10”x15” rimmed baking sheet with parchment paper (I left some overhang on the long sides and strongly recommend it) and coat with nonstick spray; set aside.
Whisk flour, baking powder, salt, and ¼ cup sprinkles in a large bowl.
Combine buttermilk, oil, and vanilla in a medium bowl.
Using an electric mixer on medium-high, beat granulated sugar, shortening, butter, and light brown sugar in another large bowl until light and fluffy, about 4 minutes. Add eggs one at a time, beating to blend between additions and occasionally scraping down sides and bottom of bowl. Continue to beat mixture, occasionally scraping down sides and bottom of bowl, until almost doubled in volume and very light, airy, and pale yellow, about 4 minutes.
With mixer on low, add buttermilk mixture until incorporated. Add dry ingredients, beating until just combined, about 1 minute.
Scrape batter into prepared pan; smooth top. Sprinkle with remaining 2 Tbsp. sprinkles. Bake until cake is light golden brown, the center springs back when gently pressed, and a tester inserted into the center comes out with a few moist crumbs attached, 30–35 minutes.
Remove cake from oven and cool on a wire rack or, in a pinch, in the fridge or freezer. The cake can be stored in the fridge, wrapped in plastic, for up to 5 days. (In the photos below, I’m showing you the prebaked cake in the 9”x13” pan because it has the 2 Tbsp. of sprinkles on it; I forgot that step when I used the proper 10”x15” pan.)
For the crumbs
Preheat oven to 300 °F. Line a rimmed baking sheet with parchment paper; set aside.
Combine flour, granulated sugar, light brown sugar, sprinkles, baking powder, and salt in a medium bowl. Add oil and vanilla, and using your hands (or a wooden spoon), mix until no dry spots remain and large clumps form when mixture is pressed together. As though you were making a crumble topping, break mixture up into clusters (some small, some large) and spread onto prepared baking sheet. Bake, stirring occasionally, until crumble is light golden brown and crunchy, 10–12 minutes (it will firm up as it cools). Let cool completely. The crumbs can be kept in an airtight container, at room temperature, for up to 5 days.
For the frosting
Combine butter, shortening, and cream cheese in large bowl of a stand mixer fitted with the paddle attachment. Beat on medium-high until mixture is smooth and fluffy, 2–3 minutes. Scrape down sides of bowl and slowly stream in corn syrup and 1 Tbsp. vanilla. Beat until mixture is silky smooth and glossy white, about 3 minutes.
Scrape down sides of bowl and, with mixer on low, add powdered sugar, salt, baking powder, and lemon juice until just combined. Increase speed to medium-high and beat until you have a brilliant stark white, beautifully smooth frosting, about 4 minutes (it should look just like it came out of a plastic tub at the grocery store!).
Frosting can be stored in an airtight container in the fridge for up to 1 week.
For the assembly
Place a piece of parchment paper on a counter. Invert cake onto it, then peel off the parchment paper (the one which was in the pan and is still stuck to the cake). Use cake ring to punch out two 6" rounds from cake (or, using a springform pan as a guide, cut out 2 rounds using a paring knife). These are your top 2 cake layers. Use the remaining cake scraps to cut out two semicircles, which will form the bottom layer of the cake.
Cut 2 strips of acetate – each should be 3 inches wide and 20 inches long.
Line a (small) sheet pan with a clean piece of parchment. Clean cake ring and place it in center of the pan. Use 1 acetate strip to line inside of cake ring. Place cake scraps inside ring and use the back of your hand to press scraps together into a flat, even layer (you never see this layer, so it’s okay that it’s messy, but since it’s the base of the cake, it needs to be flat).
Combine milk and remaining 1 tsp. vanilla in a small bowl. Dunk a pastry brush in milk mixture and use half of it to generously moisten the base layer.
Use the back of a spoon to spread about 3 Tbsp. frosting evenly over cake (I used a bit more). Sprinkle ⅔ cup birthday crumbs evenly over frosting (I recommend saving the larger, more aesthetically pleasing pieces for the top of the cake). Use the back of your hand to press them in place. Use the back of a spoon to spread another 3 Tbsp. frosting as evenly as possible over crumbs (honestly, I found it hard to do this without being a bit messy and using up a bit more frosting than 3 Tbsp. just to try to get a cleaner finish).
With your index finger, gently tuck second acetate strip between cake ring and the top ¼" of the first acetate strip, so that you have a clear ring of acetate 5–6" tall—high enough to support the height of the finished cake. Top with a cake round (if 1 of your 2 cake rounds is less pretty than the other, use it for the middle layer and save the most perfect one for the top). Brush layer with remaining milk mixture. Repeat frosting-crumb layering process.
Nestle remaining cake round into frosting. Cover top of cake with remaining frosting. Use an offset spatula to form decorative swirls (this hard to do with the acetate and it’s what I don’t like about the aesthetics of my finished cake), or do as they do at Milk Bar and shape it into a perfectly flat top. Top with remaining birthday crumbs.
Transfer cake to freezer and freeze at least 3 hours to set cake and filling.
At least 3 hours before serving the cake, pull sheet pan out of freezer and, using your fingers and thumbs, pop cake out of cake ring. Gently peel off acetate and transfer cake to a platter or cake stand. Defrost in fridge at least 3 hours. (Properly wrapped in plastic, the cake will keep up to 2 weeks in the freezer, or up to 5 days in the fridge.)