Step 1

Preheat the oven to 325°F. Lightly grease a 9" x 5" loaf pan.

Step 2

, To make the batter: Using an electric mixer at medium-high speed, beat together the butter, sugar, vanilla, baking powder, baking soda, and salt until pale and fluffy, about 3 minutes, scraping the bottom and sides of the bowl as needed.

Step 3

, Add the eggs one at a time, beating well after each addition and scraping the bowl as needed.

Step 4

, In a small bowl, dissolve the espresso powder (if using) in the warm water. Set aside.

Step 5

, Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess.

Step 6

, In a separate bowl, sift or whisk together the flour and cocoa.

Step 7

, On medium-low speed, beat a third of the flour mixture into the egg mixture in the bowl, then beat in half the water (or water/espresso). Beat in another third of the flour, the remaining water, and the rest of the flour.

Step 8

, Scrape the bottom and sides of the bowl and beat briefly to make sure everything is fully combined. Transfer the batter to the prepared pan.

Step 9

, To bake the cake: Bake the cake until a toothpick inserted into the center comes out clean, about 60 to 65 minutes.

Step 10

, Remove the cake from the oven and place it on a rack. Let it rest for 15 minutes, then carefully turn it out of the pan onto the rack to cool completely.

Step 11

, Storage information: Store any leftover cake, well wrapped, at room temperature for up to five days; freeze for longer storage.