For the donuts: Pour enough oil to cover at least 2 inches in the bottom of a heavy pan. Using a deep fry thermometer, heat oil to 375F. Do not leave unattended.
While oil is heating, open biscuit tin and lay each biscuit on a cookie sheet. Flatten each one slightly with the palm of your hand. Use a small circle cutter to cut a hole in the middle of each biscuit; keep the holes, you can fry them as well. Let biscuit dough rest for 10 minutes.
Carefully place donuts, one or two at a time, into the oil. Cook for about 1 minute on each side, or until golden brown. Using a slotted spoon, carefully lift donuts out of the oil and place onto paper towels to drain and cool completely. Once cool, coat the donuts in chocolate glaze.
For the glaze: Combine the butter with the powdered sugar in a medium bowl and blend with an electric mixer.
Add the vanilla and hot water. Mix until smooth.
Melt the chocolate chips in a microwave-safe bowl in the microwave for 30 seconds. Stir, then microwave another 15-30 seconds and stir again until completely melted. Be careful not to burn the chocolate. Add to the plain glaze mixture. Blend until smooth.
When the donuts have cooled, dip each top surface into the glaze and then flip over and cool on a plate until the glaze firms up, about 15 minutes. If desired, add some sprinkles!