I don’t have a whole lot to say about this cake. It’s easy and delicious in that moist, tender bakery-style sort of way; and it feeds a crowd. You don’t need a mixer; it’s almost a dump-everything-in-a-bowl-and-stir situation. The frosting is my favorite ever chocolate frosting: it’s swoopy and glossy and not too sweet, and if you use black cocoa and good dark chocolate it comes out basically black without a smidge of food coloring involved. I love it! Plus it’s all made in the food processor — even easier than the cake. Add a few sprinkles (the colorful ones and/or flaky sea salt) and you’ve got yourself a pretty classy sheet cake with minimal work involved.

Happy Valentine’s Day!

Note:

• If you don’t care about the color of the frosting, you can use Dutch-processed cocoa in place of black. The ultimate color of the frosting will depend on how black your black cocoa is (I got mine at a local baking goods store and it’s exceptionally dark) and what kind of dark chocolate you use. The frosting also tends to darken as it sits. The frosting isn’t too sweet — I definitely prefer it this way, but if you like a sweeter frosting, you can increase the amount of confectioners’ sugar to taste.

Chocolate Sheet Cake with Glossy Black Frosting

Makes one 9×13 cake

Ingredients

For the chocolate sheet cake:

• 284g AP flour
• 380g granulated sugar
• 84g dutch process cocoa
• 1 1/2 tsp baking powder
• 2 tsp baking soda
• 1 tsp kosher salt
• 226g sour cream, at room temperature
• 114g grapeseed oil (or other neutral oil)
• 2 large eggs, at room temperature
• 2 tsp pure vanilla extract
• 1 c freshly brewed hot strong coffee

For the glossy black chocolate frosting (adapted from Sweetapolita):

• 255g unsalted butter, softened
• 90g confectioners’ sugar
• 45g black cocoa powder
• 1/4 c hot water
• 60g / 1/4 c sour cream
• 3/4 tsp pure vanilla extract
• Generous pinch of salt
• 145g good quality dark chocolate, melted and cooled (I use Callebaut 70%)

To assemble:

• Sprinkles
• Flaky sea salt

Method

For the chocolate sheet cake:

1. Preheat the oven to 350F. Lightly grease and line a 9×13 pan with parchment paper that overhangs on the two long edges by at least a couple inches. This will make it easy to remove the cake from the pan later. (I like to secure the long edges with binder clips so the parchment doesn’t fall onto the cake in the oven.)
2. Sift together all ingredients from the flour through the salt. In a small bowl, whisk together all the remaining ingredients except the coffee. Add the wet to the dry ingredients and whisk to combine. Add the coffee and stir just until the batter is smooth. Pour the batter into the prepared pan and level the surface with an offset palette knife.
3. Bake until the cake is lightly springy to the touch and a toothpick inserted into the center comes out with a few moist crumbs (but no raw batter), about 28-35 minutes. Cool on a wire rack completely before frosting.

For the frosting:

• Combine all ingredients except the melted chocolate in a food processor and process until combined. Add the melted chocolate and process until smooth. Use immediately. (Note: the frosting is glossy as long as it stays at room temperature; it will harden and take on a more matte look after refrigeration. If you do refrigerate the cake, make sure to bring it back to room temperature before serving. It just tastes better!)

To assemble:

• Transfer the cake to a serving platter if desired. Spoon large dollops of frosting around the cake and use an offset spatula or spoon to swirl it around. Add sprinkles. Enjoy!