nonstick cooking spray
1 1/2 cups unbleached all-purpose flour
1 cup old-fashioned rolled oats
1 cup packed light brown sugar
3/4 teaspoon baking powder
1/2 teaspoon salt
1/2 teaspoon ground cinnamon
1/4 teaspoon ground nutmeg
1/3 cup apple cider or  apple juice
3 tablespoons vegetable oil
3 cups peeled, chopped tart apples, such as Granny Smith
1/4 cup coarsely chopped walnuts, toasted, optional

Preheat oven to 350 degrees. Lightly grease 9x9-inch baking pan, or coat with nonstick cooking spray.

Mix flour, oats, brown sugar, baking powder, salt, cinnamon and nutmeg in large bowl. Using fork or fingertips, work in cider and oil until mixture resembles coarse crumbs.

Press about 1 1/2 cups oat mixture firmly into bottom of prepared pan. Sprinkle with chopped apples. Mix walnuts, if using, into remaining oat mixture. Sprinkle evenly over apples, and pat into even layer.

Bake 30 to 35 minutes, or until top is golden and apples are tender when pierced with a fork. Cool completely on wire rack before cutting into bars.