Heat the oven to 375 degrees F. Butter a large baking dish and set aside. Place the apples, lemon juice and vanilla in a large bowl and toss to coat. Add the granulated sugar, 1 1/2 tablespoons flour and nutmeg, stirring to combine.
Place remaining 1 cup flour, nuts, brown sugar, cinnamon and salt in a medium bowl. Using a pastry cutter or 2 knives, cut the butter into the flour mixture until it resembles coarse crumbs. Sprinkle the mixture over the apples. Bake until golden brown, about 40 minutes. Serve warm with ice cream.
Recipe courtesy of Virginia Willis