In a food processor or blender, process the oats until finely ground. The texture should be floury, but coarser than white flour, which is totally fine. Measure out two cups of oat flour to use in the recipe (you may have a wee bit leftover, depending on the oats you started with).
In a large bowl, whisk together the oat flour, sugar, baking powder, cinnamon and salt.
Make a well in the centre of the oat flour mixture and pour in the milk, egg yolks, and melted butter. Stir to combine.
In a separate glass, metal or ceramic bowl (not plastic*), beat the egg whites to stiff peaks. Carefully fold the egg whites into the batter until no white streaks remain, but without deflating them too much. Carefully fold in the blueberries.
Lightly grease a nonstick pan or griddle over medium low heat and pour about 1/3 cup of batter into the pan. Spread the batter to form a 4 inch pancake. Two or three at a time should fit in a 12-inch skillet.
Cook the pancakes until golden, bubbles have appeared on the surface and the edges are beginning to set (about 2 minutes). Flip and cook for another minute or so, until cooked through and brown on both sides. Repeat with remaining batter.