Preheat the oven to 350°F (175°C)
Grease and flour two 9-inch round cake pans
In a large bowl, mix flour, sugar, cocoa powder, baking powder, baking soda, and salt
Add eggs, milk, oil, and vanilla extract
Beat until well combined
Stir in boiling water until the batter is smooth
Pour the batter evenly into the prepared pans
Bake for 30 to 35 minutes
Check doneness with a toothpick
Let the cakes cool in the pans for 10 minutes
Remove the cakes from the pans and cool completely on a wire rack
Frost with chocolate frosting if desired