During my time at Milkbar, we would always try to find creative ways to lower our food costs. One major method included reserving our cake scraps for future cake assembly. However, one thing that we could never figure out was how to use up the leftover soggy cereal that we would end up with after making Cereal Milk. Cereal Milk is Christina Tosi’s brainchild that came from soaking cereal into milk, then straining it out after said cereal, usually cornflakes, imparts its flavor into the milk itself. You would end up with a slightly corn-flavored, salty-ish milk that we would use in several different recipes, including ice creams, drinks, and the occasional panna cotta. However, we would also be left with gallons upon gallons of soggy cornflakes, that we usually would just throw into the compost bin because we never knew what to do with it. This recipe is my solution to that, as it utilizes both the Cereal Milk, and the soggy cereal, to create Christina Tosi’s classic Birthday Cake, but with a cereal milk, low-waste twist! The thing about the soggy cereal is that it contains a couple things worth noting: a mild corn flavor, liquid from the milk, and the cereal itself being a starch. These are all components that can be used in baked goods, especially in a cake! Breaking it down, these qualities can be used as both a flour and a milk substitution(to a degree, since the cereal still lacks gluten) and a mild corn flavoring agent. The cereal also gives any baked good a bright-yellow color, although when I think of birthday cakes, I think of funfetti yellow cake, so this kind of works perfectly with that vision! I wish I thought of it while I was still working at Milkbar, since this would have been a perfect full-circle solution to our soggy cereal problem, but at least I was able to think of it in general!

For the components, it will be a funfetti “compost” cake, a Cereal Milk soak, a cereal “compost” crunch, and Cereal Milk buttercream. I wanted to take Christina’s classic birthday cake, and combine that with both Cereal Milk and the would-be-trashed soggy cereal to bring together a lot of the things I learned and learned to love during my time at Milkbar! So we did have compost cookies, which was a fun way to say “everything but the kitchen sink”, but in this case, the term “compost” just refers to the soggy cereal that would have been composted if we weren’t using it in both the cake and the crunch. Normally when you add cornflakes to a baked good directly, they go soggy anyways. In this case, we aren’t using the cornflakes for texture – in fact, we are going as far as blending the soggy cereal up into a paste, which will make it even easier to use it in the other components. So long as you have a stick blender and/or food processor and/or spice grinder, you can make this recipe with relative ease! I have made cakes in the past using tangzhong, which is a cooked flour paste, since the gelled starches from the cooked flour cause the cake to have a moister feel to it and a springier texture. That’s a trick I learned when making milk bread, as it is the secret to making milk bread as fluffy as it is! The soggy cereal acts extremely similar to tangzhong, since it is boiled in milk, causing the corn starches to gel in the cornflakes, and the cake itself benefits greatly from that, being springy in texture, and definitely not dry. With the buttercream, as much as I wanted to do a classic American buttercream(I would never, since it’s way too sweet), I went with an ermine buttercream instead. Hermine buttercream is made with cooking out flour and milk first, and then adding butter to that. It is not only less-sweet, but a perfect way to incorporate Cereal Milk into a buttercream, since ermine buttercream is primarily milk and flour-based anyways! The recipe will taste like the most Americana yellow funfetti birthday cake you will ever have, and the best part is that you can drink a glass of cereal milk with it!

For the Cereal Milk:
1 cup cornflakes
2 1/2 cups whole milk
2 tbsp dark brown sugar
a pinch of salt

Spread the cornflakes onto a sheet tray and toast them at 350 degrees F for 10 minutes. Transfer the cereal into a pot with the other ingredients and bring to a simmer for 15 minutes. Strain out the cereal, reserving it for the puree, and allow the Cereal Milk to cool down before using.

For the compost cereal puree:
Reserved soggy cereal

Using either a spice grinder, stick blender, or food processor, puree the cereal into a fine paste. Allow that paste to cool down before attempting to use.

For the compost cake:
2 eggs, separated
3/4 cups granulated sugar, in three parts
2oz Cereal Milk
6oz compost cereal puree
1oz white or cider vinegar
4oz canola or grapeseed oil
a pinch of salt
1 tsp vanilla extract
1 cup all-purpose flour
1/2 tsp baking powder
3/4 tsps baking soda
3/4 cups rainbow sprinkles, in three parts

In a bowl, whisk the egg whites with one part of the sugar to stiff peaks. In another bowl, whisk the remaining sugar, Cereal Milk, cereal puree, egg yolks, vinegar, oil, salt, and vanilla until combined. In a third bowl, sift the flour with baking powder and soda and then toss with two parts of the sprinkles, just to coat each sprinkle in flour. Add both the flour-sprinkle mixture and the whipped egg whites into the bowl with the Cereal puree and fold until all three mixtures have combined into a single, homogenous batter. Pour and spread the batter in an even layer on a parchment-lined quarter sheet tray. Sprinkle the remaining rainbow sprinkles on top of the cake, and bake at 350 degrees F for 20 minutes. Allow the cake to fully cool before cutting out two 6-inch rounds and forming a third using the scraps.

For the compost crunch:
2oz compost cereal puree
2oz canola oil
2oz granulated sugar
4oz all-purpose flour
1/2 tsp baking powder
1oz rainbow sprinkles

In a bowl, mix the cereal puree with canola oil and sugar first. Then in another bowl, toss the flour, baking powder, and sprinkles together. Fold the flour into the cereal puree to form a dough, and crumble it into smaller, thumbnail-sized pieces. Place the dough onto a lined sheet tray and bake at 375 degrees F for 20 minutes. Allow the crunch to fully cool before attempting to use.

For the Cereal Milk ermine buttercream:
1/2 cup granulated sugar
1/4 cup all-purpose flour
a pinch of salt
1 cup Cereal Milk
2 sticks unsalted butter
1 tsp vanilla extract

In a pot, whisk the sugar, flour, salt, and Cereal Milk together on medium heat for 3-5 minutes, or until it begins to form a thick paste. Transfer the paste into a stand mixer and whip it with a paddle attachment for about 10 minutes, or until it is no longer warm to the touch. At this point, add in the butter and vanilla, and whisk it using a whisk attachment until everything is incorporated together.

For assembly:
Line a 6-inch ring mold with acetate, and place the mold onto a lined sheet tray. Place down the scrap layer of the cake first, and pour 1/4 cup(or 2 oz) of your soak onto the cake. Spread on about 1/3 of the buttercream in an even layer, using a bent spoon, and sprinkle on 1/3 of the crunch. Repeat these steps for the second layer. For the third layer, start with the soak, and then the buttercream. Transfer the cakes to the freezer first, for about 4 hours, before unmolding the cake from the acetate and ring mold. Arrange the remaining crunch on top of the unmolded cake in whatever pattern you want!