Step 1

Preheat oven to 350°F (see note). For round pans, spray pans with nonstick cooking spray, then line bottoms with parchment paper. Spray 9 x 13-inch pan with nonstick cooking spray.

Step 2

Whisk together flour, sugar, cocoa, baking soda, and salt in a large mixing bowl.

Step 3

Combine water, oil, vinegar, vanilla, and espresso powder (if using) in a large measuring cup.

Step 4

Add to the dry ingredients and whisk just until combined -- a few lumps are okay.

Step 5

Divide batter between prepared round pans, or pour batter into 9 x13 pan.

Step 6

Bake until a toothpick inserted in the center comes out clean, 28 minutes for round pans, or 32-35 minutes for 9 x 13 pan.

Step 7

Cool on wire rack. When completely cooled, frost.

Step 8

For layer cake: Cool cakes on a wire rack for 15 minutes, then invert onto the rack, removing pans. Leave cakes upside down (this flattens domed cakes) to cool completely.