Preheat oven to 375°. In a large bowl, mix together flour, brown sugar, salt and 2 tablespoons granulated sugar. Cut butter into flour blend, 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 mixture until large, moist chunks form. Transfer mixture to freezer to chill while you prepare apples.
In another large bowl, toss apples with lemon juice, cinnamon and remaining ½ cup granulated sugar. Transfer to a shallow 2-quart baking dish, and sprinkle with topping mixture. Place the baking dish on a rimmed baking sheet, and bake until golden and bubbling, 55 to 65 minutes. Let cool 10 minutes before serving. Top with a generous scoop of vanilla ice cream from your favorite Vermont producer.