Preheat the oven to 350º degrees and line an 8x8 square baking dish with parchment paper.
Melt the butter and chocolate chips together by microwaving in a microwave-safe bowl at 15 second intervals, or gently heating over the stove in a double boiler until just melted.
Whisk the eggs and brown sugar together in a large mixing bowl until foamy.
Add the melted butter, chocolate chips and vanilla, and whisking until no streaks remain.
Stir in the cocoa powder, flour, and salt.
Spread the batter evenly into the prepared baking pan and bake in center of the oven for 25 minutes or until it passes the toothpick test.
Remove and let cool.
Cookie Dough Layer:
This step is optional. Spread the flour onto a baking sheet (a layer of parchment paper makes it super easy to funnel it into your mixing bowl later). Bake in 350º oven for 10 minutes, then remove and let cool.
In a mixing bowl, cream together the butter and brown sugar, then add the vanilla, salt and milk, then flour. Lastly, fold in the mini chocolate chips.
Press the cookie dough mixture on top of the brownie layer.
Chocolate Layer:
Melt 1 cup of the chocolate chips and 3 tablespoons of the butter together in a microwave safe bowl at 15 seconds intervals until just melted. Spread on top of cookie dough layer using an offset spatula.
Refrigerate until chocolate sets.
Slice into 12-16 bars.
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