In a medium size bowl combine the brown sugar, oats, flour, cinnamon and salt. Whisk to combine.
1 cup (200 grams) brown sugar, ¾ cup (75 grams) oats, ¾ cup (110 grams) all purpose flour, 1 tsp (3 grams) ground cinnamon, ½ tsp salt
Break the softened butter up in pieces and add it to the bowl.
½ cup (115 grams) unsalted butter, softened
Using a pastry cutter or your hands, mix in the butter until it is thoroughly combined with the dry ingredients in the bowl. Your final texture should look like pea-sized clumps of dry ingredients.
Using your hands transfer the topping to your pie plate and spread it evenly so that all of your apples are covered. Press down with your hand to make a compact topping. If you like, take some extra butter and dot the top of your crust with it.
Bake in the middle rack of your oven for 50 - 60 minutes until your filing is bubbling and your crust is golden brown.
Allow to cool slightly before serving.
Apple crisp is best served warm or at room temperature.
Enjoy!