Oatmeal Bars With Dates And Walnuts

Name: Oatmeal Bars With Dates And Walnuts
Ingredients: 1 cup finely ground old-fashioned rolled oats; 3/4 cup whole-wheat flour; 1 1/2 cups old-fashioned rolled oats; 1 1/2 teaspoons baking powder; 1 1/2 teaspoons salt; 1/2 teaspoon ground cinnamon; 1/4 teaspoon allspice; 2 cups packed light-brown sugar; 12 tablespoons (1 1/2 sticks) unsalted butter, softened; 3 large eggs; 2 1/2 teaspoons pure vanilla extract; 1 1/2 cups walnuts (5 1/2 ounces), toasted and chopped; 1 cup dates (5 ounces), pitted and chopped; Vegetable-oil cooking spray