Blackout Chocolate Sheet Cake with Chocolate Cookie Crumbles
This ultra dark chocolate sheet cake is for serious chocolate lovers: with a dark chocolate glaze and a layer of crunchy cookie crumbles to top it off.
¼cup/ 60gdark chocolate chips or chopped dark chocolate
½cup/ 50gDutch-process cocoa powder, sifted*
pinchsalt
sprinkles, optional, for decoration
Instructions
For Chocolate Crumbles:
Preheat oven to 300 degrees F. Line a baking sheet with parchment paper or a silicone baking mat.
In a bowl or the bowl of a stand mixer, whisk together flour, cocoa powder, sugar, cornstarch and salt until evenly incorporated.
Drizzle in melted butter and mix until no dry ingredients remain and mixture forms rough crumbles.
Dump onto prepared baking sheet, spreading crumbles out into a single layer and breaking up any extra large pieces.
Bake for 20 minutes, stirring once part way through. Let cool completely. Crumbs can be made a few days ahead of time and stored in an airtight container at room temperature until ready to use.
For Chocolate Cake:
Preheat oven to 350 degrees F. Generously butter or grease a light or medium colored metal 13-by-9-inch baking pan (if using a dark metal or glass baking pan, I recommend reducing the baking temperature by 25 degrees to avoid overcooking).
In a bowl, whisk together flour, cocoa powder, baking soda, baking powder and salt.
In another bowl or large 4-cup glass measuring cup, whisk together sugar, buttermilk, oil, eggs and vanilla until evenly incorporated. Make a well in the center of the dry ingredients and pour in buttermilk mixture. Whisk until combined and no dry ingredients remain.
Pour into prepared pan, spreading the batter into an even layer.
Bake for 25 to 28 minutes or until center is set and a toothpick inserted near the center comes out completely clean. If it still has some moist crumbs attached to it, bake it for a few minutes more.
Let cool on a wire rack while you prepare the glaze.
For Glaze:
Combine cream, butter, sugar and corn syrup in a medium saucepan. Stir gently over medium heat until butter is melted and sugar is dissolved.
Remove from heat and stir in vanilla and chocolate chips. Gently stir until chips are completely melted (if the residual heat isn't quite enough to melt the chips, return to burner set to low for 30 seconds, then remove from heat and continue stirring).
Sifted cocoa powder over top and whisk until smooth.
Pour glaze over lukewarm cake. Generously sprinkle chocolate crumbles over top of liquid glaze, along with any sprinkles as desired for decoration.
Let cool completely at room temperature then refrigerate for at least 1 hour before slicing and serving.
Cake will keep, tightly covered in the refrigerator, for up to 3 days.
Notes
*For an ultra dark chocolate cake, substitute 2 tablespoons/20 grams of black cocoa powder in place of the Dutch process. Don't use all black cocoa, however, as it is significantly lower in fat and will result in a drier cake.
**If using thick, whole buttermilk, use 1 cup buttermilk and 1/4 cup water.