1-First Step: Preheat and Prep Your PanHeat your oven to 375°F (190°C). Grease a 9×13-inch baking pan or line with parchment for easy removal. This setup ensures your thick chocolate chip cookie bars release cleanly. For dietary tweaks, use oil spray for vegan versions.Measure dry ingredients: whisk 2 1/4 cups flour, 1 tsp baking soda, and 1 tsp salt in a bowl. Set aside. This prevents overmixing later.

2-Second Step: Cream the Butter and SugarsBeat softened butter, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes. For brown butter cookies, melt butter in a saucepan over medium heat until golden and fragrant, then cool before creaming. Scrape sides often for even texture.Add vanilla extract. Beat in eggs one at a time. This builds emulsion for chewy cookies. If using flax eggs for vegan, mix well to incorporate.

3-Third Step: Combine Wet and Dry MixturesGradually add dry ingredients to wet on low speed. Mix just until combined; overmixing toughens bars. Fold in chocolate chips and nuts by hand for even distribution.Batter should be thick. For gluten-free, let rest 5 minutes as blends absorb differently.

4-Fourth Step: Spread and BakePress batter evenly into prepared pan using wet spatula. Sprinkle sea salt on top for gourmet touch. Bake 20-25 minutes until golden edges and soft center. Rotate pan halfway for even browning.Cool in pan 30 minutes, then transfer to wire rack. For one bowl chocolate chip cookie bars, mix all in pan to skip bowls.

5-Final Step: Slice and ServeCut into 24 squares. Pair with milk or ice cream. Store as below. These easy chocolate chip cookie bars stay fresh days.