Beat together the cider, yogurt, brown sugar, egg, and vanilla.
Grind the oats until they resemble a coarse flour. Add the oats, whole wheat flour, baking soda, baking powder, salt, and spice to the wet ingredients; gently mix until combined.
Gently fold the chopped apple in to the mixture.
Use an ice cream scooper or spoon to divide the mixture into 12 lightly greased or lined muffin tins.
When you put the muffins into the oven, lower the temperature to 350 degrees and bake for 15-18 minutes.
After removing from oven, let cool in pan for ten minutes, then remove from pan.
For the glaze, beat together cream cheese, nutmeg, milk, and powdered sugar. Drizzle over cooled muffins as desired.
Notes
These muffins are light and crumbly. If you prefer a heartier muffin, add an additional 1/4 cup flour.