Heat oven to 350. Spray a 9" x 5" loaf pan w/ cooking spray. In lg bowl, combine flour, 1 cup sugar, baking powder, baking soda, 1-1/2 tsp cinnamon, salt, apples, buttermilk, oil, eggs and vanilla.
Beat 3 mins w/ a mixer. Pour into pan. In small bowl, combine 2 tbsp sugar, remaining cinnamon and butter until crumbly. Sprinkle on top of loaf. Bake 50 mins, or until a toothpick inserted in center comes out clean.