Bring first 4 ingredients to boil and simmer for 30 minutes. When fully cooked, berries and juice should equal about 32 ounces.
Make butter in 9 x 13 x 2 inch baking dish.
Mix sugar, flour and milk; pour evenly over melted butter. Add prepared blackberries and cook at 350 degrees until crust rises to top and turns light brown. Sprinkle with teaspoon sugar and dash cinnamon mixed.