Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a large mixing bowl, combine the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Whisk until well blended.
Add the eggs, milk, vegetable oil, and vanilla extract to the dry ingredients. Beat on medium speed for 2 minutes until smooth.
Carefully stir in the boiling water until the batter is well combined. The batter will be thin.
If using, fold in the chocolate chips.
Pour the batter evenly into the prepared cake pans.
Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then remove from the pans and transfer to a wire rack to cool completely.
Frost with your favorite chocolate frosting once cooled.