Preheat oven to 375°. Whisk flour, baking powder and salt. In another bowl, cream sugar and butter until light and fluffy. Add egg and milk; stir into dry ingredients. Fold in blueberries and pecans. Spread into a greased 9-in. square baking pan., For topping, combine sugar and flour; cut in butter until crumbly. Sprinkle over batter. Bake until a toothpick inserted in the center comes out clean, 35-40 minutes. Cool on a wire rack.