Start by filling your deep fryer with fresh frying oil and turning it on.
Add the egg and whole milk in a bowl with the Bisquick. Mix all of the ingredients together with a spoon. Whisk to remove any lumps.
Test to see if oil is hot enough by dripping a few small drops of batter into it. After they sizzle and turn brown, your fryer is ready for the apple rings.
Put one apple ring in the batter at a time, making sure each side is completely coated.
Drop one apple ring in at a time (our fryer will hold four rings at once). Watch carefully, when the battered apple ring begins to turn brown, flip it over to the other side with a fork. Continue to watch so they don’t burn.
Cover a baking sheet with paper towels.
When both sides of the cooked apple rings are done, remove them from the deep fryer and drain on paper towel-lined baking sheet. Allow to cool enough to touch.