In a large bowl, combine flour, sugar, baking powder, salt, cornmeal, cheese and dill; mix well.In a small bowl combine egg whites, milk and yogurt; mix well. Add egg white mixture to dry ingredients. Stir just until dry ingredients are moistened. Batter will be lumpy. Pour into spray-coated pan. 3. Bake for 14-17 min. or until top is light golden. Cut into squares and serve warm.