Pre heat oven to 350 degrees.

Grease a 4 qt baking dish with butter. Set aside.

Combine the chopped apples with cinnamon, vanilla extract and lemon juice. Pour into the prepared baking dish. Set aside.

In a medium bowl mix the flour, oats, sugar, salt, cinnamon, with a whisk until well combined. Stir in butter and with clean dry hands, crumble the mixture between your fingers until the mxture resembles peas. Add in walnuts and mix well to combine.

Sprinkle the crumble topping on top of the prepared apples.

Bake at 350 for 45 minutes or until fragrant, bubbly and golden borwn.

Serve with vanilla ice cream, a drizzle of caramel or whipped cream.