Blueberry Crumb Bars

This recipe comes from GimmeSomeOven -- it's still cooling now, so I can't say how it turned out yet, but wanted to post it while I was thinking about it...
Hopefully I can sample it soon -- the smell is amazing!
[Update...they're good, but this particular batch was labeled only "so-so" by Scott...the blueberries (I used a blend of fresh and frozen) just weren't that great...so if you have bland berries, I'd suggest increasing the amount of sugar and lemon zest perhaps, to give them more of distinct flavor]

Ingredients:
1 cup sugar (plus extra 1/3 cup for blueberries)
1 tsp. baking powder
3 cups all-purpose flour
1 cup unsalted butter
1 egg
1 tsp. vanilla extract (I actually just used some extra vanilla bean sugar in place of this)
1 tsp. salt
zest of one lemon (I only used about 1/4 of it)
4 cups fresh blueberries
3 Tbsp. cornstarch
Method:
Preheat the oven to 375 degrees F (190 degrees C). Grease a 9×13 inch pan.
In a medium bowl, stir together 1 cup sugar, 3 cups flour, salt, lemon zest, and baking powder. Use a food processor or pastry cutter to blend in the butter and egg. (Or if you don’t have these appliances, you can use an old fashioned fork or even giving it a whirl with a beater will do the trick!) Dough should be crumbly. Pat half of dough into the prepared pan.In another bowl, stir together the sugar and cornstarch. Gently mix in the blueberries. Sprinkle the blueberry mixture evenly over the crust. Crumble remaining dough over the berry layer.
Bake in preheated oven for 45 minutes, or until top is slightly brown (mine only took 30 min). Cool completely before cutting into squares.