Add enough oil to the frying pan, dutch oven, or deep fryer so that it is 2 inches deep. If using a deep fryer, set it to 350°F. If using a frying pan or dutch oven, heat the oil on medium-high heat until it reaches temperature. The oil is ready if you flick a little water into it and it boils immediately.
Keep any leftover Jelly Filled Donuts in an airtight container at room temperature. These start to go stale relatively quickly, so I recommend enjoying them within one day.