Whisk both sugars, vegetable oil, butter, and black cocoa powder in a small pot over low heat. Remove from heat once the butter is melted and the mixture is smooth.
Whisk in the eggs, vanilla extract and salt until well combined. Fold in the all-purpose flour until almost combined. Then fold in the chocolate chips until just combined.
Pour the batter into the prepared pan. Bake for 20-25 minutes or until the center is just set. Cool to room temperature then decorate brownies with spiderwebs or as desired.