• 2 c (240g) cake flour or all-purpose flour (either will work but the texture will vary a little – with the cake flour being more delicate)
• 1 tsp baking soda
• 1 tsp Diamond kosher salt
• 1/2 c unsweetened cocoa powder, such as Guittard. Do not use Dutch-process cocoa powder. 
• 1/2 c warm water
• 1/2 c buttermilk (or plain yogurt thinned with a little milk or water)
• 1/2 c water
• 2 tsp vanilla
• 4 oz (1/2 c) butter, at room temperature
• 1 c sugar
• 1 c packed light brown sugar
• 2 large eggs, beaten lightly with a fork

Preheat the oven to 350ºF.

Butter the bottom and sides of an 9″x13″ pan. Dust with flour, then tap out the excess.

Whisk the flour, baking soda, and salt together in a small bowl. Set aside.

Put the cocoa powder in a small mixing bowl and whisk in the 1/2 cup of warm water until it’s well combined.

In another small bowl mix together the buttermilk, the remaining 1/2 c water, and vanilla.

In a medium-size mixing bowl, beat the butter, sugar, and light brown sugar on low speed until they’re well combined, then increase the speed of the mixer to medium-high and beat until the mixture is light and fluffy. Stop the mixer midway during mixing to scrape down the sides.

Reduce the mixer speed to medium, then add the lightly-beaten eggs.

Continue mixing at medium speed until the batter is light and fluffy, then stop the mixer and add the cooled cocoa powder mixture and mix until it’s incorporated.

Add about 1/2 the flour mixture and stir (don’t beat) until combined. Then add about 1/2 of the buttermilk mixture and stir in. Repeat, using the rest of both mixtures. Stir just all of the flour and liquid is incorporated.

Add the batter to the prepared pan and bake until a toothpick inserted in the middle comes out clean, about 35-40 minutes.

Cool the cake in the pan on a wire rack. If you want to frost the cake (I suggest the frosting included in this recipe), wait until the cake is completely cool…but I personally think adding frosting is overkill. Instead of frosting, I’d serve the cake lightly powdered with confectioners sugar.