Grease a 15x10x1-inch baking pan; set aside. In a large bowl, stir together flour, baking powder, orange peel, baking soda, and salt. Set aside.

In a medium bowl, combine eggs, brown sugar, oil, milk, and vanilla. Stir in carrots, zucchini, cranberries, and ginger, if you like. Add egg mixture to flour mixture, stirring with a wooden spoon until combined. Spread batter in prepared pan.

Bake in a 350 degree F oven for 20 to 25 minutes or until a wooden toothpick inserted near center comes out clean. Cool in pan on a wire rack. Spread with Orange-Cream Cheese Frosting and cut into bars. Store, covered, in the refrigerator. Makes 36 bars.

In a medium bowl, beat together 1/2 of an 8-ounce package cream cheese, softened; 1/3 cup butter, softened; 1 teaspoon finely shredded orange peel; 4 teaspoons orange juice; and 1 teaspoon vanilla until combined. Gradually beat in enough sifted powdered sugar (2-3/4 to 3-1/4 cups) to make frosting easy to spread.