How to Make It
Preheat the oven to 350°. Butter a 10 1/2-by-15 1/2-inch jelly roll pan. In a large bowl, using an electric mixer, beat the butter with 1 cup of the brown sugar at medium-low speed until light and fluffy, 2 to 3 minutes. Add the egg yolks and vanilla and beat until combined. In a medium bowl, whisk the flour with the baking soda, baking powder and salt. Beat the dry ingredients into the wet ingredients just until moist crumbs form. Add the chocolate chips and pecans and stir with a wooden spoon until evenly distributed.
Scrape the mixture into the prepared pan and press to form an even layer. In a clean bowl, beat the egg whites at medium speed until soft peaks form. Increase the speed to medium high and beat in the remaining 1 1/2 cups of brown sugar, a small handful at a time, until the meringue is soft and glossy, about 7 minutes. Spread the meringue all over the dough and bake for about 25 minutes, until the meringue top is golden and crisp. Let cool completely before cutting into squares.