Four layers of rich chocolate cake, filled with delicious chocolate pastry cream and Oreo cookie chunks, frosted with creamy, silky chocolate Swiss meringue buttercream and decorated with more Oreo crumbs and chocolate ganache. I added the gummy worms on top for decoration and a little whimsy but you could absolutely leave them off. A few weeks ago my sister returned from an entire year living abroad as a Watson Fellow; traveling, researching, and being super amazing. She documented her journey through Dominica, Botswana, Australia, Tuvalu, and China on her travel blog Wanderlusting. Head on over there if you are interested in reading some of her incredible stories and more about what her Watson project to pursue the relationship between nature and writing is all about.
The weekend after she arrived home, we had a big family homecoming celebration. I told her that I would make her anything that she wanted for dessert; to which she responded "hmm, maybe the one with the pudding and the cookie crumbs." My sister-in-law asked her, "you mean like worms and dirt?" She said sure and I kind of went overboard with that idea. I decided that I wanted to do a fancier version of the classic pudding cups with chocolate cookie crumbs and gummy worms and so this cake was born. This does take a bit of time to make and has more steps than an average cake, but this recipe is great for a special occasion or if you are trying to impress your guests.
I love all of the different components and textures this cake has. The cake is moist and fluffy, yet it holds up really well against the creamy, sweet chocolate pastry cream. The cookie crumbs both inside and out keep their crunchy texture and give that familiar "worms and dirt" cookies and cream flavor profile to the cake. If you have never had Swiss meringue buttercream, it is the perfect frosting for this cake because it is not overly sweet and its silkiness is just wonderful amoungst all of the other textures. I added the chocolate ganache right on top for a beautiful smooth finish and a final punch of chocolate. The gummy worms, of course, are mostly just for show, but really who can resist a gummy worm once in awhile! Overall this cake is a beautiful array of chocolate flavors that is deliciously rich with just the right amount of sweetness.
Cookies & Cream Chocolate Blackout Cake
1/2 cup canola (or other flavorless) oil
2 cups white granulated sugar
2 large eggs
1 1/2 cups plain or vanilla greek yogurt
2 tsp vanilla extract
1 cup warm water
1 tbsp espresso powder (optional)
1 cup cocoa powder
2 cups all-purpose flour
2 tsp baking soda
1 tsp baking powder
1 tsp salt
Preheat the oven to 350°F and grease two 9" cake pans. Line the bottom of each pan with a parchment paper circle. In a large bowl, whisk the oil, sugar, eggs, yogurt, and vanilla extract together. Then add the water, espresso powder, and cocoa powder and whisk until nice and smooth. Note that the espresso powder will not make the cake taste like coffee, rather it will just increase the depth of flavor of the cocoa powder and make the cake taste more chocolaty. You could also substitute brewed black coffee for the water and espresso powder or leave it out and just use water. Switch to a wooden spoon or spatula and stir in the flour, baking powder, baking soda, and salt until just barely combined. Transfer the batter to the prepared pans and bake for 25-30 minutes, until a toothpick inserted into the center of the cake comes out clean. Let the cakes cool completely on wire racks.
Chocolate Swiss Meringue Buttercream
3 egg whites
1 cup white sugar
1 cup (2 sticks) cold butter, cubed
1 tsp vanilla extract
4 oz melted, cooled semisweet chocolate
Add the egg whites and sugar to the bowl of an electric stand mixer. Place the bowl over a pot with about 1 inch of simmering water (like a double boiler set up) and whisk until the sugar is dissolved and the egg whites are hot (about 140°F if you have a candy thermometer.) Place the bowl back on the base of your stand mixer and beat the egg whites on medium-high speed with the whisk attachment until the mixture is glossy, thick, and the outside of the bowl has cooled to room temperature. This will likely take at least 10 minutes. Switch to the paddle attachment, turn the mixer on to low speed, and begin adding small cubes of the butter, one at a time, until each is incorporated. I waited between about 10 seconds between adding each cube of butter. Don't worry if the mixture curdles or starts to look a little soupy, just keep mixing until it comes together into a smooth, silky consistency. Stop and refrigerate the buttercream for about 15 minutes if it really starts looking soupy and then continue to beat. Keep beating until all of the butter is incorporated and the frosting is smooth and glossy. You may have to beat for several minutes after adding all of the butter. Add the vanilla and melted chocolate and mix to incorporate.
Chocolate Pastry Cream
1/2 cup white sugar
1/4 cup cornstarch
1/4 tsp salt
3 cups whole milk
6 oz semisweet or dark chocolate, chopped
1 tbsp butter
1 tsp vanilla extract
1 cup heavy whipping cream
In a medium saucepan, whisk the sugar, cornstarch, salt, and one half cup of the milk together until no lumps remain. Whisk in the remaining milk slowly and turn the heat on to medium. Stir the milk mixture pretty continuously, making sure to scrap the sides and bottom of the pan to keep lumps from forming. Bring the liquid to a slow bubble and it will thicken enough to coat the back of a spoon. Stir in the chocolate and continue to cook until the chocolate is melted and the pudding is very thick. Remove the pan from the heat and stir in the butter and vanilla extract. Transfer the pudding to a bowl (you can pass the pudding through a sieve if you have any lumps) and cover the pudding directly with plastic wrap to avoid a skin from forming. Chill the pudding completely in the refrigerator. Make the pudding into pastry cream by folding in heavy cream that has been whipped to soft peaks.
1/2 cup heavy cream
4 oz semisweet or dark chocolate, chopped
Heat the heavy cream in a 2 cup glass measuring cup in the microwave for 60 to 90 seconds. Add the chocolate and let it sit for about 2 minutes and then stir until well combined. Let the ganache set to room temperature.
1 14 oz package Oreo cookies
Place the Oreos into a large plastic bag. Use a mallet or rolling pin to smash the cookies into large chunks. Remove half of the Oreos from the bag and set aside in a bowl. Crush the remaining Oreos until they are very fine crumbs and set aside. You could also use a food processor for these steps.
Remove the cakes from the pans and use a large serrated knife to cut each cake in half horizontally, creating four layers of cake. If your cakes have rounded tops, be sure to level those off as well. You want nice flat layers. Put half of your buttercream in a pastry bag (or zipper topped bag) fitted with a large star tip.
Place a small dollop of frosting onto your cake plate to keep the cake in place. Put the first layer of cake down and pipe a border of frosting around the outside edge of the cake. Fill the center of the layer with the chocolate pastry cream and one third of the large Oreo chunks. Place the second cake layer on top, repeat this process and then do it again once more with the third layer. Put the final layer of cake on top and press down lightly to even all of the layers out. Run a knife or offset spatula around the outside of the cake to clean up any of the buttercream that squished out the sides during assembly. Put the cake in the fridge for about 15 minutes to set up.
Frost the outside of the cake with the remaining buttercream. You don't have to be too neat or worry too much about crumbs because next you press the fine Oreo crumbs all over the sides of the cake. Pipe a border of stars around the top edge of the cake and then pour the chocolate ganache over the center top of the cake. Use a spoon to lightly spread the ganache out evenly. Place gummy worms on top of the cake for decoration. The cake is best eaten the day it is assembled. The components can all be made one to two days before and stored in the refrigerator until ready to assembly. Store the finished cake in the refrigerator until about 1 hour before serving.