Preheat oven to 350°. Line an 9x9” pan with foil and spray with cooking spray.
Whisk flour, baking soda, and salt in a medium bowl. Stir and set aside.
Cream butter, granulated sugar, and 1/2 cup brown sugar until combined. Turn mixer on low. Add 1 egg, mixing completely. Mix in vanilla extract. Add flour mixture to the wet ingredients and mix until combined. Mix in 1 cup chocolate chips. Press into prepared pan. Chill dough until egg whites are ready.
Beat 2 egg whites with a mixer fitted with the whisk attachment until stiff peaks form (about 3-5 minutes on speed “6” if using a stand mixer). Sprinkle 1 cup of brown sugar over the beaten egg whites, making sure there are no clumps. Fold in the brown sugar and spread evenly over the cookie layer.
Bake for 28-33 minutes or until the meringue is golden brown. If the top starts to brown too quickly, cover it with a layer of parchment paper. Let cool to at least room temperature before cutting. (Chill in the refrigerator for quicker cooling.) Peel away the foil carefully before cutting. **Be sure to spray your knife with cooking spray before cutting. After each cut wipe away excess and spray the knife again.**