In a medium bowl, stir together the 2 cups flour, the baking powder, and salt. Set the mixture aside.
In a mixing bowl, beat the 3/4 cup sugar and the 1/4 cup butter with an electric mixer until combined. Beat in egg. Add flour mixture and milk, stirring until just combined. Fold in blueberries.
Spoon batter into a greased 9x9x2-inch baking pan, spreading evenly.
In a small bowl, combine the 1/2 cup sugar, the 1/3 cup flour, and the pumpkin pie spice. Cut in 1/4 cup butter until mixture resembles coarse crumbs. Sprinkle over mixture in pan.
Bake in a 375 degree F oven for 40 to 45 minutes or until a toothpick inserted near the center comes out clean. Serve warm with whipped cream or ice cream. Makes 9 to 12 servings.