Chunky Monkey Bars

Bahan-bahan (24 porsi)

• 3 cups all purpose flour
• ¾ teaspoon salt
• 1 cup (2 sticks) unsalted butter, (at room temperature)
• 1 cup granulated white sugar
• 1 cup packed dark brown sugar
• 3 large eggs
• 1 large overripe banana, (mashed with a fork)
• 2 teaspoons pure vanilla extract
• 1 cup semisweet chocolate chips
• 1 cup chopped walnuts