Directions:

Preheat oven to 350F. Grease a 9x13-inch baking dish.
Beat oil, light brown sugar, 1/4 cup white sugar, and 1/2 teaspoon vanilla extract together in a large bowl until creamy. Add 1 egg; beat until light and creamy, about 2 minutes.
Whisk 1 1/4 cups flour, 1/2 teaspoon salt, and baking soda together in a bowl. Gradually stir flour mixture into butter mixture until dough is combined. Stir chocolate chips into dough. Spread dough into the bottom of the prepared baking dish to cover completely.
Stir 1 cup white sugar, oil, and 1 teaspoon vanilla extract together in a bowl; add 2 eggs and beat well. Mix cocoa powder into butter mixture until well-combined. Stir 1/2 cup flour, baking powder, and 1/8 teaspoon salt into cocoa mixture until batter is combined. Pour brownie batter over cookie dough and spread to cover completely.
Bake in the preheated oven until a toothpick inserted into the center of the brookies comes out clean, 20 to 25 minutes. Cool completely before cutting into bars.