1Preheat your oven to 180°C (350°F). Line an 8x8 inch (20x20 cm) baking pan with parchment paper or lightly grease it.
In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
In a large bowl, melt the unsalted butter (if not already soft). Add the brown sugar and granulated sugar, and mix until well combined and creamy.
Beat in the egg and vanilla extract until the mixture is smooth and slightly fluffy.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Do not overmix.
Fold in the semisweet chocolate chips evenly throughout the dough.
Spread the dough evenly into the prepared baking pan, smoothing the top with a spatula.
Bake for 22-25 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out with a few moist crumbs.
Allow the cookie bars to cool completely in the pan before lifting them out and cutting into squares.
Serve and enjoy your delicious Chocolate Chip Cookie Bars!