Preheat oven to 400°F. For the Apple Filling, toss apple slices with lemon juice and vanilla in large bowl. Mix cornstarch and apple pie spice in small bowl. Sprinkle over apples; toss to coat well. Spoon into 13x9-inch baking dish sprayed with no stick cooking spray.
For the Streusel Topping, mix brown sugar, flour and oats in medium bowl. Cut in butter with pastry blender or 2 knives until coarse crumbs form. Sprinkle evenly over Apple Filling.
Bake 35 to 40 minutes or until apples are tender and topping is golden brown.