Chewy Chocolate Chip Cookie Bars from King Arthur Flour

2/3 cup unsalted butter
2 cups + 2 tablespoons firmly packed brown sugar
1 teaspoon salt
1 teaspoon vanilla
3 large eggs
2 1/4 teaspoons baking powder
2 3/4 cups flour
3 cups chocolate chips

Directions:
Preheat the oven to 350. Lightly grease a 9 x 13 pan
Melt the butter, and stir in the brown sugar.  Add the salt and vanilla, stirring until well combined.
Allow the mixture to cool slightly, then add the eggs one at a time, beating well after each addition.  Scrape the sides and bottom of the mixing bowl midway through this process.
Add the baking powder and flour, stirring to combine.
Stir in the chips.
Scoop the batter into the prepared pans.  Smooth the top.
Bake the bars for 10 minutes, if using 4 small pans.