1. Preheat oven to 375 F. In a lg. bowl, mix together flour, brown sugar, salt and 2 tbsp gran. sugar. Cut butter into flour, using a pastry blender or two knives, until mixture is the texture of coarse meal. Add oats, and use your hands to toss and squeeze misture until large, moist clumps form. Transfer to freezer to chill while you prepare apples.
2. In another lg bowl, toss apples with lemon juice, cinnamon, and remaining 1/2 cup gran. sugar. Transfer to a shallow 2-qt baking dish, and sprinkle with topping mixture. Place baking dish on a rimmed baking sheet, and bake until golden and bubbling, 55 to 65 mins. Let cool 10 mins before serving.