Start heating the oil to a temperature between medium and medium-high in a medium pot. Make sure that the oil covers the bottom of the pan with about 1-2 inches of oil.
Open the can of biscuits. Watch out for that "pop!"
Separate the biscuits onto a flat surface, like a cutting board.
Using a donut hole cutter (or appropriately-sized syrup cap), punch a hole into the center of each biscuit.
Place the powdered sugar into a bowl that has a lid (tupperware works great!)
Mix the granulated sugar and cinnamon into a separate bowl or plate so that donuts can be dipped on each side.
Test the oil by placing one of the donut holes into the oil. If the hole does not start cooking right away, increase the temperature of the stove to medium-high.
Once the oil starts cooking the donuts quickly, start placing them in for about a 30 seconds to a minute per side, until browned and cooked.
As donuts come out of the oil, dry onto paper towels briefly before either shaking in the powdered sugar or covering with the cinnamon-sugar mixture.
Plate and enjoy! Best served fresh.