Preheat your oven to 350°F (175°C). Grease an 8×8-inch baking dish with butter or non-stick cooking spray.
In a large mixing bowl, combine the chopped apples, granulated sugar, ¾ teaspoon cinnamon, and lemon juice. Toss until the apples are evenly coated, then spread them into the prepared baking dish.
In a separate bowl, mix together the brown sugar, oats, flour, remaining cinnamon, and kosher salt.
Add the cold diced butter to the dry mixture. Using a pastry cutter, two forks, or your fingertips, cut the butter into the mixture until it resembles coarse crumbs with pea-sized pieces.
Sprinkle the topping evenly over the apple mixture and gently press it into an even layer.
Bake the Easy Apple Crisp for 40–50 minutes, or until the topping is golden brown and the apple filling is bubbling around the edges.
Let the crisp cool for about 10 minutes before serving. Enjoy it warm with vanilla ice cream, whipped cream, or a drizzle of caramel sauce.