Directions

Chocolate Crumble ("Dirt")

1Heat the oven at 300 degrees. Combine the flour, cornstarch, sugar, cocoa powder, and salt in the bowl of a stand mixer fitted with the paddle attachment and paddle on low speed until mixed. Add the butter and paddle on low speed until the mixture starts to come together in small clusters.

2Spread the clusters on a parchment or Silpat-lined sheet pan. Bake for 20 minutes, breaking them up occasionally. The crumbs should still be slightly moist to the touch at that point; they will dry and harden as they cool. Let the crumbs cool completely before using in a recipe or eating. Store in an airtight container, they will keep fresh for 1 week at room temperature or 1 month in the fridge.

Chocolate Chip Cupcakes

1Heat the oven 350 degrees. Combine the butter and sugars in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium-high for 2 to 3 minutes. Scrape down the sides of the bowl, add the eggs, and mix on medium-high again for 2 to 3 minutes. Scrape down the sides of the bowl once more.

2On low speed, stream in the buttermilk, oil, and vanilla. Increase the mixer speed to medium-high and paddle for 4 to 6 minutes, until the mixture is practically white, twice the size of your original fluffy butter-and-sugar mixture, and completely homogenous. Don't rush the process. You're basically forcing too much liquid into an already fatty mixture that doesn't want to make room for the liquid. Stop the mixer and scrape down the sides of the bowl.

3On very low speed, add the cake flour, baking powder, and salt. Mix for 45 to 60 seconds, just until your batter comes together and any remnants of dry ingredients have been incorporated. Scrape down the sides of the bowl. If you see any lumps of cake flour in there while you're scraping, mix for another 45 seconds.

4Spray a quarter sheet pan with cooking oil spray and line it with parchment, or just line the pan with a Silpat. Using a spatula, spread the cake batter in an even layer in the pan. Give the bottom of your sheet pan a tap on the countertop to even out the layer. Sprinkle the chocolate chips evenly over the cake batter.

5Bake the cake for 30 to 35 minutes. The cake will rise and puff, doubling in size, but will remain slightly 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 by jiggly. Leave the cake in the oven for an extra 3 to 5 minutes if it doesn't pass these tests.

6Take the cake out of the oven and cool on a wire 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.

Vanilla Buttercream

1In a stand mixer fitted with the paddle attachment, cream the butter. Start with the mixer at the lowest speed, then gradually increase the speed, using a rubber spatula to scrape the bowl as needed, until the butter is light in color, is perfectly smooth, and makes a slapping sound as it hits the sides of the bowl. This should only take 30 seconds, but if the butter is cool, it can take a couple of minutes.

2Add the sugar, 1 cup at a time, and mix at the lowest speed until it’s fully incorporated before adding the next cup. When all the sugar has been added, scrape the paddle and the bottom and sides of the bowl. Add the vanilla and salt, and beat at low speed for 15 seconds. Increase the speed to as high as you can without making a mess, and whip the buttercream until it is perfectly smooth, creamy, and light, about 5 minutes. Stop the mixer once or twice to scrape the bowl and paddle, then continue beating. At first the buttercream will appear to soften, then it will stiffen and increase in volume.

3Use right away, or store in an airtight container for up to a week in the refrigerator. When you’re ready to use it, let the buttercream come to room temperature, then put it back in the stand mixer and use the paddle attachment to beat it until it’s creamy and stiff again.

Assembly

1Mix 2 tablespoons of dark cocoa powder with 2 tablespoons of vanilla extract. Using a paintbrush, flick the tip so that the mixture speckles the Cadbury eggs. Add drops of blue food coloring to the vanilla buttercream. Ice the cupcake with the vanilla buttercream, sprinkle with chocolate crumble and then place three eggs on top.