Chocolate Chip Cookie Bars turn everyone's favorite cookie into buttery, soft, chewy bar cookies. They’re easy to make with no mixer and no chilling required. Plus, browning the butter amps ups the flavor in a big way. They're a real winner!
Preheat the oven to 350 °F. Spray the bottom and sides of a 9- x 13-inch baking pan with baking spray, then line with parchment paper leaving an overhang on the long side. Set aside.
In a saucepan with a heavy bottom, melt the butter on medium-high heat. Continue cooking the butter until it turns amber and smells nutty, about 8 minutes. Immediately remove the pan from the heat and pour the butter into a bowl to stop the cooking process. Chill the butter for about 10 minutes - it doesn't need to solidify, just cool down a bit.
Whisk the flour, cornstarch, baking soda, and salt together in a large bowl. Set aside.
In a medium bowl, mix the cooled brown butter, brown sugar, and granulated sugar together until no brown sugar lumps remain. Stir in the eggs and vanilla extract.
Add the butter mixture to the flour mixture and mix together until combined (and there are no dry spots). The dough will be very soft, yet thick.
Fold in the chocolate chips. The chips may not stick to the dough because of the melted butter but do your best to combine them. You can even use your hands to knead them in.
Transfer the dough to the prepared baking pan and press it into an even layer. Press a few more chocolate chips on top of the dough before baking (this is optional as it's just for looks).
Bake for 35 to 38 minutes or until lightly browned on the sides. Use a cake tester in the center of the pan to check if it comes out clean.
Allow the slab to cool in the pan set on a wire rack for at least an hour. Once cooled, lift the slab out of the pan using the parchment paper overhang. Cut the slab into squares (2- x 2-inches) or bars (1- x 2-inches).
Storage instructions: Cookie bars can be stored in an airtight container at room temperature for up to a week.
Make-ahead instructions: The cookie dough can be made ahead and chilled in the refrigerator for up to 3 days or frozen for up to 3 months. Allow the dough to come to room temperature before pressing it into the baking pan.
Baked cookie bars freeze well for up to 3 months. Thaw the bars overnight in the refrigerator and bring them to room temperature before serving.
Notes
You don't have to brown the butter, but doing so adds a caramelized, nutty flavor that just takes this bar up a notch. Keep an eye on the butter as it's browning as it can go from brown to burnt quickly. You’ll notice that it won’t be as noisy (the water will have evaporated), but it will be foamy. Keep checking with a spoon towards the end.You can halve this recipe to fit into a 9- x 9-inch baking pan.Use 1 egg and 1 egg yolk instead of the 3 eggs, and divide everything else in half. The bars will take less time to bake, about 32 to 35 minutes at 350°F. Yields about 32 bars.