Generously grease a 9-inch by 13-inch baking sheet with butter or cooking spray; or line the baking sheet with parchment paper. Preheat the oven to 350°F.
Place the chocolate chips in a small microwave-safe bowl. Microwave for 30 seconds then stir for a few seconds. Repeat microwaving and stirring until the chocolate chips are melted.
In a large mixing bowl, whisk together the melted chocolate chips, vegetable oil, egg, and vanilla until it is smooth.
Add the granulated sugar, brown sugar, flour, cocoa powder, baking powder and salt. Mix with a spatula or large spoon just until there is no dry flour visible. The batter will be much thicker than normal brownie batter.
Pour the brownie batter onto the baking sheet and use a spatula or the back of a spoon to spread the batter into a very thin, even layer.
Bake for 10 minutes, just until the top dries. Use a butterknife to slice the crisps into pieces while the brownies are still warm and soft. Allow to cool for at least 10 minutes, until they become crispy. Enjoy!!
Notes
Lining your baking sheet with parchment paper will help the brownie crisps be removed from the pan more easily. But it can also make spreading the batter more tedious. I usually just grease my baking sheet really well.
The batter is really thick. This is normal!
You want the batter to be spread as evenly as possible. Otherwise the thinner parts could burn and the thicker parts might remain more chewy.
Watch your brownie crisps closely in the oven. Since the batter is spread so thin, they bake really fast. You may need to adjust the baking time since there are variations between ovens.
The brownie crisps will be soft when they first come out of the oven. This is the best time to cut them into uniform pieces. Once they cool, they'll dry out and harden.