2/3 cup white whole wheat flour
1 teaspoon cornstarch
1/2 cup granulated sugar
2/3 cup cocoa powder
1 teaspoon kosher salt
6 tablespoons unsalted butter, melted
Chocolate Chip Cake:
6 tablespoons unsalted butter, at room temperature
1 cup granulated sugar
¼ cup light brown sugar, tightly packed
1/2 cup buttermilk
1/3 cup canola oil
1 tablespoon vanilla extract
1 1/2 cups all-purpose or white whole wheat flour
1 teaspoon baking powder
1/2 teaspoon table salt
1/2 cup mini chocolate chips (or regular semisweet chocolate chips, chopped into small pieces)
3 medium fresh peaches (or 1.5 cans sliced peaches, in 100% juice)
3 tablespoons sugar
Juice from half a medium lemon
1.5 tablespoons cornstarch
1/2 cup (1 stick) unsalted butter, at room temperature
1/4 cup powdered sugar
1/4 cup almond milk
3/4 teaspoon instant coffee powder (regular coffee works in a pinch)
1/4 teaspoon table salt
For the crumbs:
Heat the oven to 350 degrees Farenheit.
In a bowl, add all ingredients except for the butter and combine using an electric mixer.
Add the butter and mix on low speed until the mixture starts together in small clusters and clumps. It should resemble wet sand at this point.
Spread the crumbs on a parchment-lined sheet pan and bake for 15-20 minutes, stirring after 10 minutes. The crumbs should still be slightly most to the touch when you take them out of the oven; they will harden and dry as they cool.
Cool completely before layering in the cake. Stored in an airtight container, they will keep fresh for one week at room temperature or one month in the refrigerator.
For the cake:
With an electric mixer, cream together the butter and sugars in a large bowl on medium-high speed until pale and fluffy, about 2-3 minutes. Use a rubber spatula to scrape down the sides of the bowl, add the eggs, and mix on medium-high again for 2-3 minutes. Scrape down the sides of the bowl once more.
In a separate bowl, whisk together the buttermilk, oil and vanilla (I used a fork to whisk these in a glass measuring cup). On low speed, stream the buttermilk mixture into the butter mixture. Increase speed to medium or medium high and continue beating for 4 to 6 minutes, until the mixture is completely homogenous.
Once the mixture is completely homogenous, continue mixing at low speed and add the flour, baking powder and salt. Mix until just combined, and finish off the mixing by hand with a rubber spatula until there are no streaks of dry ingredients. Be careful not to overmix at this point, or you will end up with tough, rubbery cake. At this point, I folded in about 1/3 of my chocolate chips (the original recipe calls for sprinkling all the chips on top of the cake, which I thought was weird).
Line a 9x13” pan with parchment paper and generously grease with cooking oil or butter. Transfer cake batter to the pan and tap the pan on the countertop to even out the layer. Sprinkle the remaining chocolate chips evenly over the cake batter.
Bake the cake for 30 to 35 minutes. The cake will nearly double in size, but will remain buttery and dense. At 30 minutes, gently poke the edge of the cake with your finger: the cake should bounce back slightly and the center should no longer be jiggly. Leave the cake in the oven for an extra 3 to 5 minutes if it doesn’t pass these tests.
Take the cake out of the oven and cool on a wire cooling rack, or, in a pinch, in the fridge or freezer. The cooled cake can be stored in the fridge, wrapped in plastic wrap, for up to 5 days.
For the peach puree:
Peel and quarter peaches; add to a blender with lemon juice. Puree until smooth.
In a small pot, whisk together the sugar and cornstarch. Stir in puree, turn on pan over medium heat and whisk constantly until the mixture simmers and thickens.
Transfer the mixture to a heatproof container, and put in the fridge until the puree has cooled completely, at least 30 minutes. The puree can be refrigerated for up to one week.
For the frosting:
In the bowl of a freestanding electric mixer fitted with a paddle attachment, combine butter and powdered sugar. Cream together on medium-high for 2 to 3 minutes, until fluffy and pale yellow.
While the butter and sugar is creaming, combine the milk, coffee powder and salt in a small bowl.
Once the butter has finished creaming, scrape down the sides of the bowl using a rubber spatula. Turn on the mixer to medium-high speed and gradually, tablespoon by tablespoon, add the coffee mixture. It’s important to add this mixture slowly to help the liquids incorporate together. Eventually you’ll end up with a super shiny, fluffy frosting: it should be a consistent pale brown if you used instant coffee and a speckled brown if you used coffee grounds. Use immediately.
Cut the cake into two 6" rounds using a 6" cake ring or pan as a guide. I pressed my 6” cake pan gently into the cake, and then used a knife to do the actual cutting.
Clean off the cake ring and place it on a plate or cutting board lined with wax paper, or just a sheet of wax paper (I didn’t use a plate to save space in my packed freezer—if you don’t use a plate, just be careful to support the bottom when moving the cake). Line the inside of the ring your choice of sturdy structural material (acetate, priority mail envelopes, sturdy paper, etc). Line with parchment paper or wax paper if you are not using acetate.
Line the bottom of the cake ring with the cake pieces left from cutting out the rounds to form the bottom cake layer. Mash down the scraps with your fingers until the layer is as flat as you can get it.
Spoon 1/2 of the peach puree in an even layer on top of the cake. Reserve about ½ cup of the crumbs (more or less) for the top of the cake, and sprinkle half of the remaining crumbs evenly across the puree—this should be a thick layer. Spread 1/3 of the coffee frosting across the crumbs—it’s okay if this frosting layer is spotty; it doesn’t have to be perfect.
Place one of the full rounds of cake on top of the frosting. If one of your 2 cake rounds is prettier than the other, save it for the top. Repeat the puree, crumb and frosting process. Place the last round of cake down (this layer will not be soaked). Spread the last 1/3 of coffee frosting across this layer and top with reserved crumbs.
Freeze cake for at least three hours, or up to overnight.
Remove from cake ring, peel off your wax paper or acetate and allow to come to room temperature—approximately 2-3 hours—before serving!