Preheat oven to 350F. In a small bowl whisk together the flour, sugar, cocoa, baking soda and salt.
Make a small well in the middle of the bowl and add the water, oil and vanilla. Whisk together until smooth.
Evenly distribute the batter between two liners and sprinkle with chocolate chips if using. Bake for about 18 minutes or until a toothpick inserted into a cupcake comes out clean.
For the Frosting:
In another small bowl, use a spatula to spread the butter around making sure it's super soft and pliable.
Add the cocoa powder and stir into the soft butter.
Using the spatula, a spoon or small whisk, add the powdered sugar one tablespoon at a time until the frosting is creamy and thick.