Preheat the oven to 350°. Cut two pieces of aluminum foil and fold them to match the width of the pan. Press one piece into the pan lengthwise and the other into the pan crosswise with the ends hanging over the sides of the pan. Spray the foil with nonstick coating.
Whisk together the flour, salt, baking soda, and baking powder in a small bowl and set aside.
Using a standing mixer, a hand mixer, or by hand, cream together the butter, the granulated sugar and just 1/2 cup of the brown sugar until this looks like smooth frosting.
Separate the eggs, reserving the whites. Mix the yolks into the butter-sugar mixture one at a time until they are completely absorbed, then mix in the water and vanilla.
With the mixer at a low speed, add the flour mixture and beat gently until all the flour has been absorbed and the dough looks crumbly.
Press the cookie dough gently into the pan with your hands, making sure the surface is even.
Sprinkle the chocolate chips on top of the cookie dough and use your palms to press them slightly into the dough.
Using a stand or hand mixer with a clean bowl and a clean whisk attachment, start whisking the egg whites. Gradually increase your speed to medium-high. When the egg whites are very frothy and look like loose foam, start adding the remaining cup of brown sugar a little at a time. Continue increasing your speed to the highest setting. When all the sugar has been added, continue whipping the meringue until it holds a soft peak. It should look like glossy, soft-serve ice cream.
Scoop the meringue down the middle of the pan. It will be very sticky! Use a spatula to gently spread the meringue from the middle to the edges. We found it helpful to skim meringue from the top and gradually push it outward.
Lightly press a piece of parchment or wax paper on the top of the meringue (this makes an even layer and protects the meringue from scorching). Bake for 20 minutes, then remove the parchment. Continue baking for an additional 5-10 minutes, until the edges look toasted and are pulling away from the sides of the pan.
Wait until the pan is completely cook before lifting out the bars and cutting them into pieces.