Butter an 8 x 8-inch microwave-safe baking dish.

Arrange half of the sliced russet potatoes in the baking dish and season with salt and pepper.

Sprinkle about 1/4 of the dried rosemary over the russet potatoes.

Top with half of the sweet potato slices, then season with salt and pepper, and sprinkle with 1/4 of the rosemary.

Repeat layering with the remaining russet potatoes and sweet potatoes, seasoning each layer with salt, pepper, and 1/4 of the rosemary.

Pour or drizzle the whipping cream evenly over the potatoes.

Cover the dish tightly with heavy microwave plastic wrap.

Microwave on HIGH until the potatoes are tender, about 18-20 minutes.

Remove the plastic wrap and sprinkle both the Swiss and Parmesan cheeses over the potatoes.

Return to the microwave uncovered on HIGH for about 3 minutes, or until the cheese has melted and is bubbly.

Let cool for 10-15 minutes before serving.