1 cup (227g) sourdough starter, ripe (fed) or discard
1 cup (227g) milk (whole milk or 2% preferred) or evaporated milk
2 cups (241g) All-Purpose Flour
1 1/2 cups (298g) granulated sugar
1 cup (198g) vegetable oil
2 teaspoons vanilla extract
1 teaspoon salt
1 1/2 teaspoons baking soda
3/4 cup (64g) natural cocoa
1 teaspoon espresso powder, optional
2 large eggs
Whipped cream, optional
Instructions
Combine the starter, milk, and flour in a large mixing bowl. Cover and let rest at room temperature for 2 to 3 hours. It won't necessarily bubble, but it may have expanded a bit.
Preheat the oven to 350 degrees F. Lightly grease a 9x13 pan.
In a separate bowl, beat together the sugar, oil, vanilla, salt, baking soda, cocoa. and espresso powder. The mixture will be grainy.
Add the eggs one at a time, beating well after each addition.
Gently combine the chocolate mixture with the starter-flour-milk mixture, stirring till smooth. This will be a gloppy process at first, but the batter will smooth out as you continue to beat gently.
Pour the batter into the prepared pan.
Bake the cake for 30 to 40 minutes, until it springs back when lightly pressed in the center, and a cake tester inserted into the center comes out clean.
Remove the cake from the oven, and set it on a rack to cool.
