- 1 cup milk
- 2 teaspoons white vinegar
- 2 cups all-purpose flour
- 2 cups white sugar
- 1 cup ground flax seeds
- 1/3 cup unsweetened cocoa powder
- 2 1/2 teaspoons baking soda
- 1 1/2 teaspoons baking powder
- 1/2 teaspoon salt
- 1 cup cold-brewed coffee
- 2 eggs
- 3 tablespoons vegetable oil
- Preheat oven to 350 degrees F (175 degrees C). Grease a 9×13-inch baking pan.
- Mix milk and vinegar together in a small bowl. Let sit until curdled, about 5 minutes.
- Mix flour, sugar, ground flax seeds, cocoa powder, baking soda, baking powder, and salt together in a bowl. Make a well in the center of the flour mixture; add milk-vinegar mixture, coffee, eggs, and vegetable oil. Beat with an electric mixer until batter is well mixed.
- Pour batter into the prepared baking pan.
- Bake in the preheated oven until a toothpick inserted into the center comes out clean, 25 to 30 minutes.