Preheat oven to 325 degrees (I know... not 350, they will dry out). Since you are hopefully using a silicone baking pan, there is no need to grease the pan, however, if you are using a metal pan, then insert baking cups (I like the foil ones).
Grind the oats in a blender, then transfer to a bowl and set aside.
Before making the batter, chop up your apple and place in a bowl with the 2 Tbsp. water and microwave for 2 minutes. If you are not a microwave fan, you can also cook them on the stove.
Now add the rest of your ingredients to the bowl of ground oats. Once the apples are done in the microwave, drain them and add to the batter.
Mix the apples into the batter well, then use a ¼ cup measuring cup and pour the batter into each muffin cup.
Bake for 15-18 minutes, or until the tops of the muffins are slightly firm.