- 2 cups all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 1/4 teaspoons baking soda
- 3/4 teaspoon salt
- 1 1/2 sticks (3/4 cup) unsalted butter, softened
- 1 3/4 cups packed light brown sugar
- 2 large eggs
- 1 teaspoon vanilla
- 1 1/3 cups water
- Confectioners sugar for dusting
- Preheat oven to 350°F. Butter a 9- by 2-inch round cake pan and dust with flour, knocking out excess.
- Whisk together flour, cocoa, baking soda, and salt.
- Beat together butter and brown sugar with an electric mixer until pale and fluffy. Add eggs 1 at a time, beating well after each addition, then beat in vanilla.
- Add flour mixture and water alternately in batches, beginning and ending with flour and mixing just until combined.
- Pour batter into cake pan and bake in middle of oven until springy to the touch and a tester inserted in center comes out clean, 55 minutes to 1 hour. Cool in pan 1 hour. Invert onto a rack, then turn right side up and dust with confectioners sugar.