Freeze Snickers halves for at least 4 hours. Heat oil in a large pan to medium-high temperature.
Mix flour and water to make a smooth, thick batter. Carefully dunk each piece of Snickers into the batter and place straight into the hot oil, cooking 2 to 3 at a time. Fry for 2 to 3 minutes or until golden brown all over. Remove from the oil with tongs or a slotted spoon and place on paper towels. Leave to cool for a couple of minutes before dusting in powdered sugar.