Mix together the wet ingredients (egg, milk, oil) until well combined.
Add in the flour, baking soda, and 1 tablespoon of sugar. Whisk until combined and no large clumps of flour remain, but do not overmix.
Prepare the cinnamon sugar filling by mixing together butter, cinnamon sugar, and 1 tablespoon of the pancake batter.
Heat a tablespoon of butter in a skillet over medium heat. Once melted and bubbling, scoop a large ladle of the pancake batter onto the skillet and immediately cover with a lid.
Let the pancake cook for about 30 seconds, then swirl the cinnamon sugar mixture on top. Cover the lid again and let cook for 4-5 minutes until the pancake is done.
Repeat with remaining batter and cinnamon sugar mixture.
Serve the pancakes stacked with a generous amount of icing and butter on the side.
