Preheat oven to 350 degrees F. Lightly grease a 9x13x2 inch baking pan; set aside.
In a large mixing bowl, stir together 2 cups flour, rolled oats, brown sugar and ground cinnamon. Cut in butter with a pastry blender until mixture resembles coarse crumbs. Remove 1 1/2 cups of the crumbs; set aside.
Press remaining crumbs into bottom of prepared baking pan. Bake in the preheated oven for 15 minutes.
Meanwhile, in a medium mixing bowl, beat eggs and granulated sugar with whisk until smooth. Whisk in the 2 tablespoons flour, then baking powder and salt. Stir in pears or apples and cinnamon pieces. Gently spread fruit mixture over the baked crust. Sprinkle with reserved crumb mixture.
Bake in a 350 degree oven for 30 to 35 minutes more or until golden brown. Cool in pan on a wire rack. Cut into bars. Drizzle with powdered sugar icing.
To make powdered sugar icing: In a small bowl stir together 1 cup sifted powdered sugar and 1 tablespoon milk. Stir in additional milk 1 teaspoon at a time, until icing is of drizzling consistency.
Cover and store bars in refrigerator for up to 1 weeks. DO NOT FREEZE.