Two-Layered Apple Crisp Recipe

In a large bowl, beat the butter, brown sugar, cinnamon and salt until crumbly. Add flour and oats; mix well. Press 3 cups oat mixture into the bottom of a greased 13-in. x 9-in. baking dish. In another bowl, mix the first five filling ingredients. Add apples and vanilla; toss to combine. Spoon over oat layer. Dot with butter; sprinkle with remaining oat mixture. Bake, uncovered, at 350 ° for 45-50 minutes or until golden brown and apples are tender. If desired, serve with toppings.