Preheat oven to 350. In a large mixing bowl, cream shortening & 1/2 cup of sugar. Add egg. Mix well. Combine 2 cups flour, baking powder, & salt in a small bowl. Add to creamed mix alternating with milk. Beat well after each addition.
Spread in to greased 9 x 9. Toss blackberries with lemon juice. Add to pan. In a small bowl combine cimmamon, sugar, and remaining flour. Cut in butter until mixture resembles coarse crumbs. Sprinkle over berries.
Bake for 45-50 minutes or until toothpick inserted in center comes out clean.