Gingerbread Bars

Bahan-bahan (12 porsi)

• 1/2 cup (1 stick) unsalted butter, (at room temperature)
• 1/3 cup packed dark brown sugar
• 3/4 cup molasses
• 2 large eggs
• 2 teaspoons freshly grated orange zest
• 2¼ cups all purpose flour
• 1½ tablespoons ground ginger
• 1 teaspoon ground cinnamon
• 1/2 teaspoon ground cloves
• 1/2 teaspoon ground nutmeg
• 1/2 teaspoon baking soda
• 3/4 cup buttermilk
• 3/4 cup milk chocolate chips ((optional))