Devil Dog Cake

Directions

1. 1
   To make cake:.
2. 2
   Preheat oven to 350°F with rack in middle. Butter and flour a 9-inch square cake pan (2 inches deep).
3. 3
   Whisk together flour, cocoa powder, baking soda, and salt.
4. 4
   Beat together butter and brown sugar with an electric mixer until pale and fluffy. Add eggs 1 at a time, beating well, then beat in vanilla.
5. 5
   Add flour mixture and water alternately in batches, beginning and ending with flour mixture and mixing until just combined.
6. 6
   Pour batter into cake pan and smooth top, then bake until a wooden pick inserted in center comes out clean, 45 to 55 minutes.
7. 7
   Cool in pan on a rack 1 hour.
8. 8
   Transfer cake to a cake plate.
9. 9
   Make frosting:.
10. 10
    Combine frosting ingredients with a pinch of salt in a metal bowl set over a saucepan of simmering water and beat with a handheld electric mixer at high speed until frosting is thick and fluffy, 6 to 7 minutes.
11. 11
    Remove bowl from heat and continue to beat until slightly cooled.
12. 12
    Mound frosting on top of cake.
13. 13
    Dust with additional cocoa powder.
14. 14
    Cooks' notes:.
15. 15
    Cake, without frosting, will improve in flavor if made 1 day ahead. Cool, then keep, wrapped in plastic wrap, at room temperature. Frost cake just before serving.
16. 16
    The egg whites in the frosting are not fully cooked. You can substitute pasteurized or reconstituted dried egg whites if salmonella is a problem in your area.