1. In a medium bowl combine flour, oats, brown sugar, and baking soda. Using a pastry blender, cut in butter until the mixture resembles coarse crumbs. Reserve 1/2 cup of the crumb mixture.
2. Press remaining crumb mixture into the bottom of an ungreased 9x9x2 or 11x7x1 1/2 baking pan. Spread with desired filling. Sprinkle with reserved crumb mixture. Bake in a 350 oven for 30-35 minutes or until the top is golden. Cool completely in pan on a wire rack. Cut into bars.
Apricot Filling: In a medium saucepan combine 1 cup of snipped dried apricots and 3/4 cup of water. Bring to boiling; reduce heat. Simmer, covered, for 5 minutes. Meanwhile, combine 1/4 cup sugar and 1 tablespoon all-purpose flour; stir into apricot mixture. Cook and stir about 1 minute more or until thickened and bubbly.
Apple-Cranberry Filling: Combine 1 cup chunky applesauce, 2/3 cup dried cranberries or blueberries, 1/2 teaspoon ground cinnamon and dash of ground cloves.
Easy Filling: Use 1 1/2 cups canned mincemeat or 1 21-ounce can of cherry or peach pie filling.
Raisin Filling: In a medium sauce pan combine 3/4 cup water, tablespoons sugar, and teaspoons cornstarch. Add 1 1/4 cup golden raisins. Cook and stir until thickened and bubbly.
To Store: Place in layers separated by waxed paper in an airtight container; cover. Store at room temperature up to 3 days or freeze up to 3 months.