Melt the butter in a pan over a medium heat. Turn off the heat once the butter is fully melted and set aside.
In a large bowl, whisk sugar, eggs and milk together. Slowly sift in the flour and until it forms a smooth and liquid batter. Add the cinnamon and whisk well.
Place the mixture in the fridge for an hour.
Heat the oil in a large non stick pan on high temperature. Ladle the batter into the pan making sure it spreads out evenly along the pan. Cook on each side for about 3 minutes.
Continue this until all the batter is used.
Before serving, place about 4 apple slices onto each crepe and fold over.