1½ cups unsalted butter, softened to room temperature

2 cups brown sugar, packed

½ cup granulated sugar

1 large egg

1 egg yolk

2 teaspoons vanilla extract, pure extract

2½ cups all-purpose flour, spooned and leveled

1 teaspoon baking soda

½ teaspoon salt

2 cups semisweet chocolate chips, or dark chocolate chips

Sea salt flakes, optional for topping

Preheat the oven to 350°F (175°C) and line a 9x13 inch baking pan with parchment paper, leaving an overhang for easy removal.

In a large mixing bowl, beat the butter, brown sugar, and granulated sugar together with a hand mixer until light and fluffy, about 2-3 minutes.

Beat in the eggs, egg yolk, and vanilla extract until just combined.

In a separate bowl, whisk together the flour, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, mixing until just a few streaks of flour remain.

Fold in the chocolate chips with a spatula until evenly distributed.

Transfer the dough to the prepared pan and press it evenly into the corners.

Bake for 25-30 minutes, until the edges are golden brown and the center is slightly soft.

Allow to cool completely in the pan, then lift out and cut into 12 bars. Optional: Sprinkle with sea salt flakes on top after baking for an extra flavor boost.