Preheat oven to 350 degrees. Spray a standard size muffin pan with cooking spray and set aside.
In a large bowl, combine the oats, sugar, baking powder, salt, and cinnamon.
In a separate smaller bowl, mix together the eggs, milk, and butter.
Stir the wet ingredients into the dry ingredients then fold in the blueberries. Pour the oatmeal mixture into the prepared muffin pan, about 1/3 cup each.
Bake for 18-20 minutes until edges of muffin cups are golden brown and fully cooked. Remove from oven and allow to cool before removing from pan and serving.
These can be stored in the refrigerator for 1 week in a container with a lid or in a large resealable plastic bag. To reheat, place on a microwave safe plate and microwave on high for 30-45 seconds. Enjoy!