Preheat oven to 400°F and grease a muffin pan.
In a large bowl, stir together flour, oats, sugars, cinnamon, baking powder, and salt.
In another bowl, stir together milk/water, eggs, oil, and vanilla until blended.
Make a well in centre of dry ingredients and add wet ingredients, stirring just to combine.
Stir in apple.
Spoon batter into prepared muffin cups and bake for 15-20 minutes or until a muffins pass the toothpick test.
Allow muffins to cool on a wire rack for five minutes before removing from pan to continue cooling.
Serve warm or completely cooled. Muffins can be frozen.
