This is simply the best chocolate cake we have ever tried! Moist and rich, the true secret ingredient here is the Koikuchi Marudaizu Soy Sauce in the frosting. It adds just a little salty note that really pulls the cake together. We LOVE IT!

Ingredients

Makes one 9-by-13-inch frosted cake

For the cake:

1 cup (2 sticks) plus 1 tablespoon unsalted butter, at room temperature

2 1/3 cups all-purpose flour

1/2 cup cocoa powder

1 1/2 teaspoons baking powder

1/2 teaspoon baking soda

1/2 teaspoon sea salt

1 3/4 cups buttermilk

2 teaspoons pure vanilla extract

2 1/4 cups light brown sugar

3 large eggs

8 ounces semisweet or bittersweet chocolate, finely chopped, and melted (see Note)

For the frosting:

10 tablespoons (1 1/4 sticks) unsalted butter, at room temperature

1 cup confectioners’ sugar

4 ounces bittersweet chocolate, finely chopped, melted, and cooled to room temperature (see Note)

2 tablespoons Koikuchi Marudaizu Soy Sauce Naogen

1 teaspoon pure vanilla extract

Step 1

Make the cake: Preheat the oven to 350°F. Grease a 9-by-13-inch glass or metal cake pan with the 1 tablespoon of room temperature butter.

Step 2

Whisk together the flour, cocoa, baking powder, baking soda, and salt in a large bowl. Combine the buttermilk and vanilla in a medium bowl or a 2-cup liquid measuring cup.

Step 3

In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl, if using a handheld mixer), cream the 1 cup of butter and the brown sugar on low speed until creamy and well combined. Increase the speed to medium-high and beat until light and airy, about 2 minutes. Reduce the mixer speed to medium-low and add the eggs one at a time, mixing well between each addition and scraping down the side and bottom of the bowl as needed. Once all 3 eggs are added, beat for 1 minute on medium speed to get the mixture nice and fluffy.

Step 4

Reduce the speed to medium-low and add the flour mixture alternately with the buttermilk mixture in three batches, starting with the flour. Add the melted chocolate and mix on medium speed until well incorporated, stopping the mixer to scrape down the side and bottom of the bowl as needed.

Step 5

Use a rubber or offset spatula to scrape the batter into the prepared pan and even it out as much as possible. Bake until a cake tester inserted into the center of the cake comes out clean and the center of the cake resists light pressure, about 40 minutes. Remove from the oven and set aside to cool completely, at least 2 hours, before frosting.

Step 6

Make the frosting: Put the butter in the bowl of a stand mixer fitted with the whisk attachment (or in a medium bowl, if using a handheld mixer). Beat on medium-high speed until smooth. Turn off the mixer and sift the confectioners’ sugar into the bowl and combine on low speed. Add the melted chocolate, soy sauce, and vanilla and beat on low speed until combined. Increase the mixer speed to medium-low and whip until glossy, 15 to 30 seconds.

Step 7

Use an offset spatula or butter knife to spread the frosting on top of the cooled cake. Cut into squares and serve.

Step 8

Let it sit out at room temperature for 15 to 20 minutes before slicing and serving.

Koikuchi Marudaizu Soy Sauce Naogen Chocolate Cake