Heat oven to 400*. Mix 1/2 c. Sugar and cornstarch in saucepan. Stir in berries and lemon juice. Cook, stirring constantly, until mixture thickens and boils. Boil and stir 1 min. Pour into ungreased casserole (2 qt); keep hot in oven. Cut shortening into flour, 1 tbsp sugar, the baking powder and salt until crumbly. Stir in milk. Drop dough by 6 spoonsful onto mixture. Bake 25-30 min.