Preheat the oven to 350 degrees, line an 8x8 glass baking dish with foil, then lightly spray with non-stick spray. Set aside,
First, make the brownie layer:
In a large bowl, add the sugar, flour, cocoa powder, salt, baking powder, and chocolate chips. Use a spatula to mix until well combined.
In a measuring cup, add in the oil then eggs, and vanilla. Mix up the wet ingredients with a fork.
Pour the wet ingredients into the dry ingredients and stir with the spatula until just combined.
Spread the mixture into the prepared baking dish and set aside.
Now make the peanut butter cookie:
To a large mixing bowl, add the butter and sugars and whisk until light and fully combined.
Add in the whisked egg and vanilla and combine.
Add in the peanut butter and stir with a spatula.
Add in the flour, baking soda, and salt, and mix until fully combined.
Use your hands to flatten pieces of the dough and lay on top of the brownie layer. Fit the pieces together, like a puzzle, until you have a fairly even layer covering the brownie batter.
Bake for 40-45 minutes or until the cookie layer is golden brown and a toothpick inserted in the center comes out clean.
Let cool for 20 minutes then lift out the foil and cut into bars.
Notes
Feel free to take a shortcut & use a box mix for the brownie layer - just make sure you don't get a family size. Ghirardelli makes a great one.Peanut Butter Cookie recipe from Picky Palate