When you say "whole", do you mean unpeeled, or just uncut?
Roughly what size do you use, and how long to cook? (As you can see,
you've got me thinking about a harvest.

Sweet potatoes may be cooked whole with the skins on, which is how they are
cooked in the microwave. The skin is edible & probably good for you. However,
when you microwave them whole, you have to stab them to the center to keep them
from exploding. Size doesn't matter, except it is easier to cook several nearly
the same size. Length of time depends on your microwave. Look at the
instructions.

I'd never have thought of molasses in that.

Neither did I. Standard recipe calls for plain sugar or brown sugar.

Iris,
Central NY, Zone 5a, Sunset Zone 40
"When you come to a fork in the road, take it." Yogi Berra