I don't like to use the microwave for softening butter, because it doesn't seem to soften evenly. I take my refrigerated butter and grate it with the large holes on a box grater. It softens pretty quickly this way.

Thanks, all...20 seconds did the trick and cookies are in the oven!

I do 5 second intervals and touch it each time. I stop early, when it can be lightly squeezed. The melting point comes soon.

I run my microwave at med heat in 10 second intervals.

About 17 seconds but that's my microwave.

Depending on the strength of the microwave, I'd start out at 20 seconds and check the butter. Normally the butter will start to melt before completely soft, so I opt for underdone rather than too melted, using the heat from creaming to melt the rest.