Preheat oven to 375 degrees F. Line a 9x13 rectangular light metal baking pan with foil, extending the sides of the foil over the edges of the pan. Spray the foil liberally with cooking spray; set aside.

For the crust and crumb: In a large bowl, combine the sugar, baking powder, salt and flour and mix well. Add in the cubed butter, beaten egg and vanilla and using a pastry cutter or two forks, cut the butter into the flour mixture until the mixture resembles small pebbles. Dough will be crumbly.

Press half of the dough mixture into the prepared pan, using your hands to compact it into a neat, even layer. Set aside.

Meanwhile, in a medium bowl, combine the blueberries, sugar, cornstarch, lemon juice and lemon zest, tossing to coat. Pour the blueberry mixture evenly over the crust in the pan. Sprinkle the remaining crust dough over the top.

Bake for 38-45 minutes or until the crumble topping is light golden brown, the blueberry mixture is bubbly and the bars appear set. Cool completely for at least an hour or two before cutting into bars, or you may refrigerate.