Preheat your oven to 350°F (175°C) and grease or line a 9-inch round cake pan.
In a bowl, sift together the flour, baking powder, baking soda, salt, and cocoa powder.
In another bowl, whisk the granulated sugar, brown sugar, eggs, vanilla extract, and vegetable oil until smooth. Add the milk and stir to combine.
Gradually add the dry ingredients into the wet mixture, mixing until smooth. The batter will be thick.
Slowly mix in the boiling water to thin the batter, then fold in the chocolate chips (optional).
Pour the batter into the prepared pan and bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
Allow the cake to cool before serving.