Preheat oven to 350F (175C) and line a metal 9×9" (23x23cm) baking pan with parchment paper, leaving enough to hang over the sides so you can easily lift the bars out of the pan once cooled (alternatively, if you plan on serving in the pan you may bake directly in a lightly greased baking pan).

Combine butter pieces and chopped chocolate in a medium-sized heatproof bowl and heat in the microwave in 25-second increments, stirring in between, until chocolate and butter are completely melted and mixture is smooth.

Add cocoa powder, sugars, eggs, vanilla, instant coffee (if using), and salt and stir until well-combined.

Add flour and stir well. If using chocolate chips, stir these in now as well.

Spread batter evenly into prepared baking dish. Transfer to 350F (175C) oven and bake for 30-35 minutes or until a toothpick inserted in the center comes out clean or with fudgy crumbs (but not wet batter).

Allow to cool before assembling, but in the meantime you can begin to prepare cookie dough topping. If you are going to be making your cookie dough topping right away, do not turn off your oven.

Preheat oven to 350F (175C) and line a cookie sheet with parchment paper.

Spread flour in an even layer over the parchment and transfer to 350F (175C) oven. Bake for 7 minutes or until temperature of flour reaches at least 160F (71C). I scoop the flour into a mound and check the temperature with an instant read thermometer. Allow flour to cool before proceeding.

In a separate bowl, use an electric mixer to beat together butter, sugars, vanilla extract and salt.

Sift the cooled baked flour over the butter mixture and beat until all flour is absorbed. If the mixture is still dry and crumbly no matter how much you beat it, add 1-2 Tablespoons of milk or cream, as needed.

Stir in mini chocolate chips.

Spread cookie dough evenly over cooled brownie layer.

Combine chocolate chips and shortening in a heatproof bowl. Heat in the microwave in 20-25 second increments, stirring in between, until mixture is melted and cooled.

Pour over cookie dough layer and use a spatula to spread evenly.

Allow chocolate to cool until set before cutting and serving. You may transfer to the refrigerator to speed up the process, if desired.