Blend rolled oats in a blender for 20-25 seconds to a fine flour with no large pieces remaining.
Add protein powder, baking powder, and salt to the blender. Pulse twice to combine.
Add eggs, Greek yogurt, milk, and vanilla extract. Blend on low for 15-20 seconds until smooth and pourable.
Rest the batter uncovered for 3-5 minutes until small bubbles appear on the surface.
Heat a non-stick skillet over medium heat with 1 tsp oil or butter until the fat shimmers and butter stops foaming.
Pour 3 tablespoons of batter per pancake, spacing at least 3cm apart. Cook 2-3 minutes until edges are set and 3-4 bubbles have broken open and stayed open.
Flip once with a thin spatula. Cook for another 90 seconds until the bottom is golden brown and the center springs back when pressed. Repeat with remaining batter.