In a separate bowl, whisk together the milk, maple syrup, oil (or butter), eggs, and vanilla. Make a well in the center of the dry ingredients, then pour the wet ingredients into the center.
In a large bowl, stir together the whole wheat flour, oats, oat flour, baking powder, cinnamon, salt, and nutmeg.
Preheat the oven to 400 degrees F. Lightly grease a standard 12-cup muffin tin or line with paper liners and set aside.