Preheat oven to 350 F degrees.
Prepare an 8×8 baking dish by buttering the dish or spraying it with non-stick cooking spray. Set aside until needed.
Add the dry ingredients (with half of the cinnamon) to a large bowl.
Add the cold butter cubes to the flour mixture.
Use your hands to cut the butter into the oat mixture until the mixture resembles pea-sized crumbs. Set aside while you prepare the apples.If you have a pastry cutter, it’s a great tool for making the crunchy topping for the apple crisp. Add the sliced apples, granulated sugar, the other half of the cinnamon, and lemon juice to a large bowl.
Mix the ingredients together until the tart apples are well coated with the cinnamon sugar creating the perfect apple filling.
Pour the apple mixture into the prepared baking dish.
Add the crumble topping on top of the apples. Smoothing the topping so its evenly distributed.
Place the apple crisp on the center rack of the preheated oven and bake for 40-50 minutes, until golden brown and bubbly.
Serve warm with a scoop of vanilla ice cream and enjoy!