– The cake relies on the last-minute combination of vinegar and baking soda for leavening. The reaction between the two causes the batter to bubble vigorously, and thus, rise.
– The cake has to be prepared in its baking pan; otherwise it doesn’t rise nearly as well. Make wells in the dry ingredients and add the wet ingredients — oil, vinegar, and vanilla — to the wells, and then add water and stir quickly (but not too much) to blend the batter just moments before you put it into the oven. Streaks of flour should remain.
Serves 6 to 8
1 1/2 C all purpose flour
3/4 C sugar
1/4 C natural cocoa powder
3/4 tsp baking soda
1/2 tsp salt
5 TBSP vegetable oil
1 TBSP distilled white vinegar
1 tsp vanilla extract
1 C water
1. Adjust oven rack to middle position and heat oven to 350 degrees. Coat 8-inch-square baking pan with nonstick cooking spray.
2. Whisk flour, sugar, cocoa, baking soda, and salt together in pan. Make one large and two small craters in dry ingredients. Add oil to large crater and vinegar and vanilla separately to remaining small craters. Pour water into pan and mix until just a few streaks of flour remain. Immediately put pan in oven.
3. Bake until toothpick inserted in center of cake comes out with a few most crumbs attached, about 30 minutes. Cool in pan, then dust with confectioners’ sugar. (If tightly wrapped, cake will keep for 3 days at room temperature.)