Best Ever Apple Crisp

For the Topping

old-fashioned or quick-cooking oats3 Honey Grahams, finely crushed (about 1/2 cup)1/3 cup packed brown sugar1/3 cup flour1/4 cup chopped pecans1/3 cup butter1 tsp. ground cinnamon, divided

For the Apple Filling:

packed brown sugar2 Tbsp. flour5 Granny Smith apples, peeled and sliced (about 6 cups)