Chewy Cookie Bars

Ingredients

• 2 cups + 2 Tablespoons all-purpose flour
• 1/2 tsp. kosher salt
• 1/2 tsp. baking soda
• 12 Tablespoons unsalted butter, melted and then cooled to room temperature
• 1 cup packed light brown sugar
• 1/2 cup sugar
• 1 large egg + 1 large egg yolk
• 2 tsp. pure vanilla extract
• 2 cups mix-ins (chocolate chips, PB chips, nuts, etc.)

Directions

1. Preheat oven to 325° F. Line a 9" x 13" metal baking pan (do not use a glass pan for this recipe) with heavy duty foil, letting the excess hang over the edges of the pan on the long sides of the pan. Lightly spray the foil-lined pan with non-stick spray.
2. In a medium bowl, whisk together flour, salt, and baking soda; set aside.
3. In a large bowl, whisk together melted butter, brown sugar, and sugar until combined. Add egg, egg yolk, and vanilla. Whisk until well combined.
4. Fold dry ingredients into the wet mixture. When about half-way combined, add mix-ins (chocolate chips, nuts, etc.) and continue to fold until just combined. Do not over mix.
5. Transfer mixture to prepared pan. This will be very thick. Press evenly into pan using the spatula and/or your fingertips. If desired, sprinkle a few more chocolate chips over the top, pressing them in a bit.
6. Bake for about 234 minutes or so, or until top is light golden brown and slightly firm to the touch. For the chewiest bars, do not over bake. 
7. Remove pan to wire rack to cool to room temperature. Cut around perimeter of pan to loosen, and then lift bars from pan using the foil overhangs. Transfer to cutting board and cut into squares with a knife or rigid pastry cutter.

Notes
- To double this recipe: Double the ingredients and follow the instructions, baking the bars in a 13x18 pan. The dough will be thick when mixing all of the ingredients, and there will be alot of it. Spread dough evenly into the pan. Bake at 325°F for 29 to 30 minutes, or until top is light golden brown and slightly firm to the touch. For the chewiest bars, do not over bake.

Source
https://www.afarmgirlsdabbles.com/chewy-chocolate-chip-cookie-bars/