Rinse and scrub any excess dirt off of the potatoes, slicing larger ones in half. Cook the potatoes for 30 minutes or until just fork tender. Drain well then add to a large mixing bowl.
Using a hand mixer on the lowest setting, or a potato masher, mash or mix the potatoes until they break apart and begin to resemble a "mashed" consistency.
To the potatoes, pour in the heavy cream, add in the butter, and sour cream, then mix again on a low setting to combine.
Add in the garlic powder and dried parsley, and the sprigs of fresh rosemary, mixing again until everything is combined and the potatoes are creamy and blended.