Mix the Dry Ingredients

• The base of your fruit bar's crust consists of equal parts all-purpose flour and whole-wheat flour -- regular or pastry version -- but beyond that, you're free to experiment with what you have on hand or what aligns with your family's dietary requirements. Include 1 part chopped nuts or rolled oats, or a mixture of both, add a few tablespoons of wheat bran or germ, about 1/2 teaspoon salt and choose your sweetener. Try granulated sugar, brown sugar, maple syrup, honey or molasses. For every 1 1/2 cups of flour, add approximately 1/2 cup of sweetener. Put the ingredients into a blender or food processor and pulse until any nuts you've added are ground.

Blend in the Wet Ingredients

• Whisk whole eggs, egg whites or egg substitute in a bowl along with a neutral vegetable oil such as canola oil and flavor extracts such as vanilla or almond. Plan on using one egg, several tablespoons of oil and a few teaspoons of extract for each 1 1/2 cups of flour. Put small cubes of cold butter or trans-fat-free margarine into the dry mixture in the blender -- approximately 4 tablespoons for 1 1/2 cups flour -- and process until the ingredients are blended and there aren't any large chunks remaining. Add in the egg mixture and run the crust batter, pulsing frequently, until it clumps on the sides of the machine. If you'd like, remove some of this batter to save as the topping for the finished fruit bars.

Prepare the Fruit Filling

• If you're making bars that contain a total of 1 1/2 cups of flour, prepare about 4 cups of fruit. This can be diced fresh fruit such as apples, frozen fruit such as blueberries, canned drained fruit, dried fruit, fruit preserves or a combination of several types. Stir a liquid such as water or juice into the fruit, adding 1/2 cup for every 4 cups of fruit. Mix in an equal amount of your sweetener, then add half as much cornstarch. Simmer the fruit filling mixture in a saucepan until it's very thick. For more texture and additional flavor, stir in some chunks of uncooked fruit and spices such as cinnamon, nutmeg, cardamom or ginger.

Assemble and Bake

• To assemble the fruit bars, lightly coat a baking dish with nonstick cooking spray, scrape the crust batter in and press it into an even layer along the dish's base. Spread the fruit filling mixture across the top. Arrange any reserved crust batter across the top of the fruit for the topping, adding some extra chopped nuts or oats if desired. Bake the bars until the ingredients are set and the crust is brown, around 45 minutes total, with the first 15 minutes at 400 degrees Fahrenheit and the remaining half hour at 350 degrees. Wait at least 1 1/2 hours before cutting into the bars to allow it to set completely.