Blackberry Breakfast Bars

16 Oz blackberries, fresh, frozen or canned
2 1/2 Tablespoons cornstarch
1 Tablespoon lemon juice
1 Cup white enriched flour
1 Cup whole wheat flour
2 Cups quick rolled oats
1 Cup brown sugar
1 1/4 Teaspoons baking powder
3/4 Teaspoon salt
1/2 Teaspoon ground allspice
1 Teaspoon cinnamon
1 Cup butter or margarine

These bars are great for breakfast or for a quick snack. Use a 13"X9"X2" pan. Set oven temperature to 400 degrees. Thaw berries and warm in saucepan until the juices run. Reserve one cup of juice, adding water if necessary to make one cup. Combine cooled reserved juice with cornstarch and lemon juice. Cook and stir until thickened. Stir in blackberries. Set aside. Combine flour, oats, brown sugar, baking powder, salt and spices. Cut in butter until crumbly. Press 2/3 of mixture into greased baking pan. Bake 15 minutes or until lightly browned. Cool slightly; spread blackberries over this crust. Crumble remaining flour/oat mixture over berry layer and press lightly. Bake 20- 25 minutes more, until lightly browned. Cool in pan.