In a 425 degree oven, bake the sweet potatoes on a baking sheet for one hour or until easily pierced with a sharp knife in the center.

When cool enough to handle, split each potato in half.

Carefully scoop the insides out into a medium bowl, leaving the skin as a hollow shell.  

Next, mash the potatoes with a fork or blend for even smoother texture.

Add the rosemary, onion powder, garlic powder, sage, salt, and butter. Stir until well combined.

Using a spoon, return the potato mixture back into the skin shells. Top each potato half with a sprinkling of parmesan cheese.  

Drop the oven temperature to 325F degrees. Place the potatoes back in the oven for 10-15 minutes or until the cheese has melted.