In a medium mixing bowl, blend together 1 1/2 cups flour, sugar, baking powder, salt, oil, milk, egg and 1 cup blueberries. Beat thoroughly for 30 seconds and spread in a greased round 9x1-1/2-inch pan or an 8x8x2-inch pan.
Combine 1/3 cup flour, brown sugar, cinnamon and butter. Sprinkle over batter and top with the remaining berries. Bake in a 375F oven for 25 to 30 minutes, until done. Don't overbake.