Preheat the oven to 350 degrees.
In a medium bowl, combine the butter, flour, ½ cup of the brown sugar, the oats, walnuts, and salt. Using a wooden spoon (or clean hands), mix until well combined. Gently fold in the cheddar cheese, then set aside.
Peel, core, and thinly slice all the apples and place them in a large bowl. In a small bowl, whisk together the lemon juice and the cornstarch until completely smooth. Add this mixture to the apples, along with cinnamon and the remaining ¼ cup sugar. Toss well. Transfer the apples to a 9x9-inch square baking dish and spread into an even layer. Crumble the topping mixture evenly on top, covering the entire surface of the apples.
Bake for 40 to 50 minutes until bubbling and golden brown on top. Cool for 10 minutes, then serve with scoops of vanilla ice cream.Copyright 2019, Lidey Heuck, All Rights Reserved