In a large bowl, combine oats and buttermilk, stirring to mix. Cover the bowl with plastic wrap and refrigerate at least 2 hours to overnight.
When ready to cook the pancakes, remove the oatmeal mixture from the refrigerator. Add the beaten eggs, melted butter, vanilla extract to the oat mixture, stir well.
In another bowl, combine the flour, sugar, baking powder, baking soda, cinnamon, and salt. Add the flour mixture to the oat mixture, stirring to blend. Stir gently, just enough to moisten the dry ingredients. Over mixing will lead to tough pancakes because the gluten in the flour begins to develop as soon as liquid touches it, and the more you mix, the tougher the gluten becomes. There will be some small lumps in the batter, so do not worry about them.
Heat a large frying pan or cast-iron skillet or griddle over medium heat until fairly hot and until a drop of water skitters across the pan. Lightly coat your pan with vegetable oil. Do not use butter as it burns too quickly.
Ladle approximately 1/4 cup of the pancake batter onto the hot griddle, taking care not to crowd the pancakes. Cook the pancakes, turning once, until deep golden brown on both sides, approximately 5 minutes total. A pancake is ready to be turned over when it's dry around the edges and bubbles have formed over the top. You are allowed to peek to see if the bottom is golden brown before you flip it.
Either serve immediately or transfer the cooked pancakes to a large plate, keep warm in oven. Repeat process with additional oil and remaining pancake batter.
Serve hot, topped with butter and maple syrup. Fresh fruit is also excellent.
Makes 12 pancakes or 3 to 4 servings.
* If you don't have buttermilk, use the Buttermilk Substitution Recipe.
** I have also substituted vegetable oil.
Healthy Oatmeal Pancakes Recipe: https://whatscookingamerica.net/bread/oatmealpancakes.htm