Heat oil in a large pot or dutch oven to 375 degrees using a thermometer. It's easiest when the thermometer clips to the side of the pot to ensure the temperature is consistently at 375 degrees.
Place 2 paper towels on a wire rack where you will place donuts when they come out of the hot oil. Set up another wire rack next to the first one for the glazing station. You may want to place a paper towel underneath to catch excess glaze for easy clean up.
Mix glaze ingredients together until smooth. Add more hot water as needed for the consistency desired. I like mine to be fairly thin.
Separate biscuits and cut circles in the center of each disk. Roll each cut out into 8 balls (these are for the donut holes). Place donuts 2 at a time into hot oil until golden. Flip onto other side and fry again until golden. This should only take about 1 minute for each side. Scoop donuts out with a slotted spoon and place on paper towel lined wire rack. Repeat the frying process for the rest of the donuts and donut holes. In between each batch, coat the hot donuts in glaze on both sides by dunking each side quickly. Set them on the second bare wire rack to let the excess drip off onto the paper towels underneath. Remember to keep a consistent temperature of 375 degrees the entire time while frying and adjust heat settings as needed.
Donuts are best served warm and fresh! A few hours later and you may have to reheat in the microwave for a few seconds. The second day, the donuts will soak up the glaze and aren't as fresh anymore but are still tasty when warmed up.