Preheat the oven to 350°F and spray an 8x8-inch baking pan with non-stick cooking spray.
In a large mixing bowl, combine 6 peeled and chopped Golden Delicious apples, 2 Tbsp granulated sugar, 2 tsp lemon juice, and ½ tsp ground cinnamon. Toss until the apples are evenly coated.
Pour the apple mixture into the prepared baking pan and spread it evenly.
In a separate bowl, combine 1 cup brown sugar, ¾ cup old-fashioned oats, ¾ cup all-purpose flour, ¼ tsp salt, and the remaining 1 tsp ground cinnamon.
Add ½ cup butter cut into small pieces and use a pastry cutter or two forks to work the butter into the dry ingredients until the mixture becomes crumbly.
Sprinkle the crumble topping evenly over the apple mixture.
Bake for 40–50 minutes, or until the filling is bubbling and the topping is golden brown.