Add the rolled oats to a blender and pulse for 30 seconds until they form a fine flour-like consistency.
Add the whole wheat flour, sugar, baking powder, baking soda, and salt to the blender with the oat flour. Pulse 2-3 times to combine evenly.
In a large mixing bowl, whisk together the buttermilk, egg yolks, melted butter, and vanilla extract until smooth.
Pour the dry oat mixture from the blender into the wet ingredients and stir gently with a spatula just until combined, leaving a few small lumps.
In a separate clean bowl, beat the egg whites with a hand mixer on high speed until soft peaks form, about 2 minutes.
Gently fold the whipped egg whites into the batter in two additions, being careful not to overmix. Let the batter rest for 5 minutes to thicken.
Heat a griddle or large skillet over medium-low heat and lightly grease with butter or oil.
Pour 1/4 cup batter per pancake onto the hot griddle, spacing them 2 inches apart. Cook for 2-3 minutes until bubbles form across the surface and edges look set.
Flip carefully with a spatula and cook for another 1-2 minutes until golden brown and cooked through.
Transfer to a plate and keep warm while you cook the remaining batter. Serve immediately with your favorite toppings.
