If using rolled oats, pulse them in a food processor or blender until they form a fine flour-like powder. If you started with oat flour, skip this step.
In a medium bowl whisk together the Greek yogurt, eggs, maple syrup, vanilla and lemon zest until smooth and uniform.
Stir the oat flour, baking powder, cinnamon and salt together in a separate bowl to distribute the leavening evenly.
Fold the dry mixture into the yogurt mixture with a spatula until mostly combined. Add the milk a tablespoon at a time to reach a thick batter that still drops slowly from a spoon — it should be thicker than classic pancake batter.
Let the batter rest 5 minutes while you heat a large nonstick skillet or griddle over medium-low. The short rest allows the oats to hydrate and helps the pancakes puff.
Melt a little butter in the hot pan and wipe it around with a paper towel to coat the surface thinly. Spoon about 1/4 cup batter per pancake onto the skillet, leaving room between each.
Cook on the first side until bubbles form on the surface and the edges look set, about 2–3 minutes. For extra lift, cover the pan loosely for 30–45 seconds during the first side so steam helps the centers set.
Flip carefully and cook the second side 1–2 minutes more until golden. Transfer to a plate and keep warm while you finish the rest, adding more butter as needed between batches.
Serve stacked with fresh berries and an extra drizzle of maple syrup if you like.