In a medium sized bowl, mix flour, milk, vanilla extract, egg, and sugar until you get a smooth batter.
Using a potato peeler or knife peel skin off apples, then slice into 5 or 6 slices. If you have a corer, core the apples. If not use a small cookie cutter to cut a hole in the center.
Dip each ring in the batter, insert your fork inside the hole and let it drip a bit before putting it in hot oil (about 350 degrees). I use a cast iron skillet for deep-frying these as they are thin. This way I don’t waste too much oil. Any kind of frying pan will work.
Remove apples from the oil and immediately sprinkle the cinnamon sugar mixture on. This will allow it to stick to the batter. Remove excess grease by placing on a plate lined with paper towels.
Note: This batter is not real sweet. If you find you want them a little sweeter, dust them with powdered sugar as well.