• Preheat oven to 350 degrees F. Line an 11x7-inch baking dish with parchment paper or spray with nonstick cooking spray. (You could also use a 9x13 pan but the brownies will be thinner.)

Cookie Layer

• In a medium mixing bowl or stand mixer with the paddle attachment, beat softened butter, ½ cup granulated sugar together until fluffy; about 1-2 minutes.
• Beat in egg yoke and vanilla for another minute.
• Gently stir in flour, pinch of salt, baking powder and 1 teaspoon ground cinnamon, just until combined. Set aside.

Brownie Layer

• Place butter and chocolate chips in a microwavable, medium-sized mixing bowl. Microwave on high for 30 seconds. Stir, and continue microwaving and stirring in 30 second intervals until chocolate is melted. (This took about 1 minute for me).
• Beat in sugar, then vanilla and eggs, until well combined.
• Stir in flour and a pinch of salt, just until combined.

Assembly

• Pour the brownie batter into the prepared baking pan.
• Drop teaspoon-sized scoops of cookie dough evenly over the brownie batter.
• Using a thin knife, gently swirl the batter into the dough a few times.
• In a small bowl, stir together 2 tablespoons granulated sugar and 2 teaspoons ground cinnamon. Sprinkle evenly over the batter.
• Bake in the preheated 350 degree oven for about 40 minutes. Check for doneness with a toothpick.
• Allow to cool before cutting into squares and serving.