To begin, preheat your oven to 350 and spray a muffin tin with non-stick spray.
To a large mixing bowl, add your butter and brown sugar and whisk them together till thoroughly combined. Add your applesauce, vanilla, and eggs and briefly blend them in. While whisking, add your milk.
To the same bowl, add your oats, cinnamon, nutmeg, baking powder and salt and stir till combined. Add your apple and zucchini and stir it into the oatmeal batter.
Fill each muffin cavity all the way full. Bake in the oven for 18-22 minutes, or till the oatmeal is springy to touch and a toothpick inserted comes out clean.
Let cool entirely, then run a knife around the outside of each oatmeal cup and gently remove them.
Devour!
Stored in an airtight container in the fridge these last about a week.