Remove half of the crumb mixture from the mixing bowl and set aside to use on top of the blueberry pie bars.
Press the other half of the crust mixture into the prepared baking pan. Bake for 15 minutes, just until crust is beginning to brown.
Spread blueberry pie filling over the baked crust. Use a spatula to spread into an even layer.
Sprinkle the remaining crust mixture over the blueberry pie filling. Bake the blueberry bars for 15-20 minutes longer, until the bars are light golden brown.
Whisk together powdered sugar and the milk or cream to make the glaze. You can also add a few drops of almond extract in the glaze.
Drizzle sugar glaze over the cooled blueberry pie bars.
Lift cooled bars from the pan and cut into squares. Or simply cut and serve straight out of the pan.