Preheat the oven to 350 degrees. Prepare an eight-by-eight-inch or nine-by-nine-inch baking pan by spraying it with cooking spray, and set it aside.
Rinse the blueberries and then dry them well (I spread mine on paper towels to let them really drain).
In a large mixing bowl, add all of the filling ingredients. Stir well to coat the blueberries evenly, and place the blueberry mixture in the refrigerator while you make the topping.
In another mixing bowl, combine all of the topping ingredients, except the butter, and stir well to combine. Cut in the butter with two knives, a fork or a pastry cutter until it's well distributed and the mixture is in small crumbs.
Pour the blueberry mixture into the prepared baking dish, spreading it evenly. (Be sure to scrape the mixing bowl to get all the juice, too.) Evenly distribute the topping over the filling, and bake the crisp for 40 to 50 minutes, or until the topping is lightly browned.
Serve warm and refrigerate any leftovers in a sealed container.