Prep: Slowly heat the 2 cups vegetable oil in a deep cast iron skillet or prepare the deep fat fryer. Set a plate next to your fryer with a thick layer of paper towels. Mix the sugar and cinnamon for the cinnamon sugar coating in a medium bowl and set it next to the paper towel lined plate. Add a large plate for the finished fritters.
Make apple fritter batter: In a large bowl whisk together the flour, sugar, cinnamon, baking powder and salt. Add the milk, maple syrup, egg and 1 tablespoon oil and whisk until a thick and smooth batter forms.
Check the oil: Check if your oil is hot enough by dropping a small amount of batter into it. If the batter browns and quickly floats to the surface you're ready to go!
Fry the apples: Using metal tongues coat an apple ring with batter and gently drop it into the hot oil. Fry for 1-2 minutes on each side until golden and puffy. Remove from the oil and quickly drain on the paper towels. Toss it in the cinnamon sugar mixture while still warm and set aside on the plate. Proceed in the same way with the remaining apple slices until the entire batter has been used. Depending on the size of your skillet or fryer you can do multiple rings at the same time.