Place all the ingredients except for the grated apple in your blender. Blend until the batter is completely smooth (as in, you should not see any remaining bits of oats or hear oats hitting the blades), pausing to scrape down the sides as necessary. Stir in the grated apple but do NOT blend again.

Heat a heavy cast iron skillet/non-stick pan over medium-low heat, or heat an electric griddle to 350 degrees Fahrenheit. Lightly oil the surface of your pan with coconut oil, butter or cooking spray. If using a non-stick electric griddle, you might not need any oil at all.

Once the surface of the pan is hot enough that a drop of water sizzles on it, pour about ⅓ cup of batter onto the pan. This batter is thick, but your pancakes won't cook through if they're thicker than ½-inch, so you might need to help spread the batter out with a spatula. Let the pancake cook for about 3 minutes, until bubbles are popping up and the edges are more matte than shiny. (Be patient, these pancakes need to cook a little lower and slower than most.)

Once the underside is lightly golden, flip it with a spatula and cook for another 90 seconds or so, until golden brown on both sides. You may need to adjust the heat up or down at this point to avoid burning the outsides before the insides are cooked. Repeat with remaining pancakes.

Serve the pancakes immediately or keep warm in a 200 degree Fahrenheit oven.