To prepare the brownie layer:

1. Preheat the oven to 350 degrees and line an 8 or 9” square baking pan with aluminum foil. Lightly grease the bottom with baking spray.
2. Melt the butter over medium heat until just barely melted. Pour into a medium-sized mixing bowl and whisk in the sugar and brown sugar. Whisk in the egg and vanilla. Add the flour, cocoa powder, and salt and stir with a wooden spoon until almost combined. Add the chocolate chips and stir until the ingredients are well incorporated. Spread the mixture into the bottom of the prepared pan. You can use lightly moistened fingers to pat it out evenly.

To prepare the cookie layer:

1. Melt the butter over medium heat until just barely melted. Pour into a medium-sized mixing bowl and whisk in the sugar and brown sugar. Whisk in the egg and vanilla. Add the flour, baking soda, baking powder, and ½ teaspoon salt and stir with a wooden spoon until almost combined. Add the chocolate chips and stir until the ingredients are well incorporated. Spread the mixture on top of the brownie layer. Sprinkle the top of the cookie with the remaining ¼ teaspoon of salt and then bake in the preheated oven for about 35 minutes or until a toothpick inserted just barely comes out clean. Allow to cool on a cooling rack for about 20 minutes before pulling the aluminum foil and bars out. Once cooled, slice into squares.