Start by melting the unsalted butter in a saucepan over medium heat. Stir continuously until the butter turns a golden brown color and develops a nutty aroma, which should take about 5-7 minutes. Be careful not to let it burn!
In a mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. This ensures that your dry ingredients are evenly distributed.
In a separate bowl, mix the brown sugar with the browned butter until well combined. Beat in the egg and vanilla extract until the mixture is smooth and glossy.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Be careful not to overmix, as this can lead to dense bars.
Fold in the semi-sweet chocolate chips or chunks, followed by the dulce de leche. Swirling the dulce de leche into the batter creates delicious pockets of sweetness.
Preheat your oven to 350°F (175°C). Line your baking pan with parchment paper or grease it lightly. Pour the batter into the pan, smoothing it out evenly. Bake for 20-25 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean.
Once baked, remove the pan from the oven and let the bars cool completely in the pan. Once cool, lift the parchment paper out and slice into squares. Enjoy your Dulce de Leche Brown Butter Chocolate Chip Cookie Bars warm or at room temperature!
