Preheat oven to 325°F. Spray a 9-inch round cake pan with cooking spray and line the bottom with parchment.

In a saucepan over low heat, melt the chocolate chips and butter together until smooth. Remove from heat and let cool slightly.

In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt.

In a large mixing bowl, add in the melted butter chocolate mixture. Whisk in the sugars, water, oil, milk, egg, and vanilla. Stir!

Add the wet mixture into the dry ingredients, folding gently with a spatula until just combined. Do not overmix.

Pour batter into the prepared pan, smoothing the top.

Bake for 35–40 minutes, or until a toothpick inserted in the center comes out with moist crumbs (not wet batter).