Preheat the oven to 350 degrees F. Line a 9X13-inch pan with parchment paper leaving an overhang on the sides for easy removal and cleanup (I use metal; glass will bake differently). Lightly grease parchment and sides of pan with nonstick cooking spray. Set aside.

For the brownie layer: in a medium microwave-safe bowl, add the butter, granulated sugar, cocoa powder, and salt. Cook for 45-second intervals, stirring in between, until butter is melted and mixture is smooth. Don't over heat. Let cool slightly until warm to the touch not hot. Add the vanilla and mix with rubber spatula until combined. Add the eggs, one at a time, stirring vigorously after each one. When the batter looks thick, shiny and well blended, add the flour and mix until no dry streaks remain. Then beat vigorously for 40 strokes with a rubber spatula. Spread evenly in the bottom of the lined pan.

For the chocolate chip cookie bar layer: In a medium bowl using an electric hand mixer whip together the softened butter and sugars until light and fluffy, 2-3 minutes. Add the egg and vanilla and mix until combined. Sprinkle salt and baking soda over top and flour and mix just until no dry streaks remain. Stir in ¾ cup chocolate chips. Scoop spoonfuls of cookie dough and gently press into a layer on top of the brownie layer. Sprinkle remaining ¼ cup chocolate chips on top.

Bake in preheated 350 degree F oven for 25-30 minutes until bars are set and lightly browned on top. A toothpick inserted in the middle may come out with moist crumbs but not gooey batter. Add time, if needed, being careful not to overbake.

Let bars cool completely on a wire rack. For easier cutting, refrigerate to chill completely. Cut into bars and serve chilled or at room temperature. Bars freeze well.