Prick the sweet potatoes about six times with a kitchen fork Place the sweet potatoes on the turntable of the microwave oven like the spokes of a wheel, atop a layer of paper towels.
Microwave on high for seven minutes, then turn them over (careful--they may be very hot). Microwave another seven minutes. Let them stand in the microwave for about seven more minutes, then check to see if they’re soft. If not, microwave in two-minute bursts until the potatoes are fully soft.
As soon as the potatoes have cooled enough to safely handle, scoop them into the food mill and crank them through into a bowl. Add the butter and the cream, and whisk until blended. Add all the other ingredients, and whisk until smooth.
