Preheat oven to 400 degrees Fahrenheit. Pierce each potato multiple times with a fork. Wrap each in foil, and back until tender, about 45 minutes.
Allow sweet potatoes to cool for a few minutes. Peel and cut into large chunks and place into a bowl. Add half n' half, butter, garlic, sea salt, basil and rosemary into a small sauce pan, and bring to a simmer over low heat.
Pour half n' half mixture little by little over sweet potatoes, mixing and mashing in with a wooden spoon. (You may not use all of this mixture, or you may need to add a little more half n' half to achieve the texture you desire).