Peanut Butter Cookie Bars

Bahan-bahan (24 porsi)

• 1 cup unsalted butter (softened to room temperature)
• 1 cup creamy peanut butter
• 1½ cups light brown sugar (tightly packed)
• ½ cup granulated sugar
• 1 large egg (+ 1 large egg yolk)
• 2 teaspoons vanilla extract
• 2¾ cups all-purpose flour
• 1 teaspoon cornstarch
• ½ teaspoon baking powder
• ¼ teaspoon salt
• 2 tablespoons milk
• 2 cups chocolate chips (semisweet or milk chocolate)