Preheat oven to 350ºF, and line an 8-inch square pan with parchment paper leaving extra overhang on the sides for easy removal. Combine graham cracker crumbs, sugar, cinnamon and melted butter in a medium bowl. Press mixture into the bottom of the pan and bake for 10 minutes.

In a medium saucepan over medium heat, melt the butter. Remove from the heat and stir in the cocoa powder until smooth and glossy. Whisk in both sugars. Add the eggs and vanilla, stirring until fully incorporated. Switch to a wooden spoon and stir in the flour, salt, and baking soda. Stir in the chocolate chips.

Pour batter over the graham cracker crust. Bake for 25-28 minutes. Remove from the oven and allow to cool completely.

Add the egg whites* and sugar to a large heatproof bowl and set over a saucepan of barely simmering water. Heat mixture, stirring constantly, until it the temperature hits 160ºF on a candy thermometer, about 3-5 minutes.

Remove bowl from saucepan, add the cream of tartar, and beat mixture with an electric hand-mixer (or in a stand mixer) on high speed until stiff glossy peaks form, about 6-8 minutes. Add the vanilla near the very end. Spread on top of the cooled brownies. Toast the topping with a kitchen torch or under the oven broiler.

Run a knife along the edges of the brownies. Carefully lift the brownies out of the pan, by using the parchment overhang. Cut into squares and serve.