Prep Oven & Filling:Preheat the oven to 350°F (175°C) and grease a 9×13-inch baking dish. In a large bowl, combine the sliced apples, sugar, flour, cinnamon, salt, lemon juice, and vanilla extract. Toss until the apples are evenly coated.
Assemble the Crisp:Transfer the apple mixture to the prepared baking dish, spreading it into an even layer.
Make the Topping:In a separate bowl, mix together the oats, flour, brown sugar, cinnamon, and salt for the topping. Add the cold butter cubes and use your fingers to rub the butter into the dry ingredients until the mixture is crumbly.
Bake:Sprinkle the crisp topping over the apples, covering them completely. Bake the apple crisp for 45-50 minutes, or until the topping is golden brown and the apples are tender when pierced with a fork.
