Apple Notes: I usually end up with about 5 to 7 cups of sliced apples. The amount of sliced apples doesn't need to be exact, but I like to use a minimum of 5 cups. Keep in mind that they do cook down quite a bit. Also, you can cut the apples into chunks, instead of slices, if you prefer. Large diced apple can be easier to eat! See the post above for recommendations on the types of apples to use.
Vanilla Option: Stir ¼ teaspoon vanilla extract into the vanilla before drizzling it on.
Whole Wheat Option: Substitute whole wheat pastry flour for the all-purpose flour. The taste will be just slightly heartier. If you use regular whole wheat flour, the crumb will be noticeably denser. Whole wheat pastry flour has a lighter, finer grind.
Berry Option: You can toss a cup of seasonal fresh berries with the apples for more flavor contrast. Blueberries and raspberries are popular.
Nut Option: You can reduce the oats by ¼ to ⅓ cup and add the equivalent amount of chopped nuts. Chopped walnuts or pecans or sliced almonds go nicely.
Butter Alternative Note: I use a salted dairy-free butter alternative. If you opt to use an unsalted option, I would add a little very fine salt, maybe ⅛ to ¼ teaspoon, to taste.