Preheat the oven to 350°F (175°C).
In a large bowl, mix flour, cocoa powder, baking soda, and salt.
In another bowl, whisk together sugar, coffee, milk, oil, eggs, and vanilla.
Combine the wet and dry ingredients, mixing until smooth.
Pour batter into a greased 9-inch cake pan.
Bake for 35-40 minutes or until a toothpick comes out clean.
Let the cake cool before serving. Optionally, sprinkle with chocolate chips.