Mix cinnamon sugar:
In a small bowl, mix together the sugar and cinnamon. Put aside.Prepare paper towels:
Prepare a plate lined with paper towels and set it aside. Also have a second plate or serving tray ready for the finished donut holes coated in cinnamon sugar.Heat frying oil:
Pour frying oil into a Dutch oven and heat over medium heat. Use a candy thermometer to heat the oil to 350°F (175°C).Cut biscuit dough:
Use a small round cookie cutter to cut each biscuit, then form the leftover dough into balls of similar size.Fry donut holes:
When the oil is ready, fry the donut holes in batches of 5 or 6 for about 1 minute per side, until they turn golden brown.Coat in cinnamon sugar:
Place the fried donut holes on the paper towel-lined plate for about a minute. While still warm, move them to the bowl with the cinnamon sugar and toss to coat evenly. Transfer them to a separate plate.Turn off heat:
After all donut holes are fried, turn off the heat under the oil.