Prep: 1. Preheat oven to 375. Grease an 8 or 9 inch baking dish. 2. Juice lemon. Make: 1. Toss together the blueberries, sugar, cornstarch, salt and lemon juice. Dump into the prepared baking dish. 2. In a bowl, combine the oats, almonds, baking powder, salt, sugar, and, butter. 3. Crumble the mixture together with your hands until butter is about pea sized and then sprinkle over the blueberry mixture. 4. Bake until topping is golden and juices are bubbling, about 1 hour. If the topping browns too quickly, cover with aluminum foil. 5. Let sit 20 minutes before serving to let filling set.