The smooth, subtly bitter flavor of dark chocolate in a fluffy dessert.
Turn the oven up to 350 F and grease and flour a 9x13-inch pan.
In a big bowl, combine the flour, sugar, cocoa, baking soda, baking powder and salt. Make a little well in the center of the mix, and pour in the eggs, coffee, milk, oil and vinegar. Mix that stuff until it's smooth, and don't worry if it's a little thin. Pour the batter into the prepped pan.
Bake the pan in the preheated oven for 35 to 40 minutes. If you can stick a toothpick in and pull it out clean, it's all done. Take it out of the oven and let it cool completely.