Add oats and buttermilk to a large bowl. Mix well.
Place bowl, covered, in the refrigerator, for 2 hours or overnight.
When ready to cook pancakes, add eggs and melted butter to oat mixture.
In a separate bowl, sift together flour, sugar, baking powder, baking soda, cinnamon and salt. Add to oat mixture.
Preheat griddle to hot.
Add oil.
Spread out batter with the back of the ladle.
When bubbles appear, gently flip cakes and cook until golden brown, about 5 minutes per side.
Serve hot with more butter and maple syrup.