Step 1 Grind the rolled oats in a blender until they are as fine as flour. Combine the oats, flour, sugar, salt, baking powder, baking soda and cinnamon in a large mixing bowl.
Step 2 In a medium bowl, mix together the lightly beaten eggs and the buttermilk.
Step 3Stir the buttermilk mixture into the flour mixture in a few quick strokes. All of the dry ingredients should be moistened, but don't worry if there are a few small lumps. That's better than overbeating, which will toughen the pancakes. You should have about 4 cups of batter.
Step 4Heat a griddle or frying pan over medium-high heat until it's hot enough that a drop of water skitters and dances across the surface. Brush the pan lightly with butter and then ladle out the pancakes in roughly one-fourth-cup amounts. Cook until the bubbles stop rising from the bottom and the top surface looks slightly dried out, 3 to 4 minutes.
Step 5Flip the pancakes and continue cooking until the center feels lightly set when you press the top with your fingertips, about 2 minutes more. Adjust the heat of the griddle as needed so the pancakes cook evenly. Keep the pancakes warm in the oven until all are cooked. This makes about 16 to 18 pancakes.