Yes you can. Shift up once into an easier gear, while maintaining the same speed. After you get the hang of that, shift into the next easier gear, keeping the original speed.

You can also work on it while going down hill. When you start going down, resist the urge to shift into a higher gear, and keep pedaling in the same gear you were in before the downhill. Depending on the hill, you may have to shift eventually, but delay your shifts until you are spinning faster than you're used to.