Preheat oven to 400 degrees.
Place potatoes in a single layer in a glass baking dish. Melt butter in a skillet over medium heat. Add garlic and cook until golden. Stir in rosemary and cook just until a fragrance is released. Pour over potatoes in dish and season with salt and pepper.
Roast uncovered for about 30 minutes in preheated oven or until potatoes are fork tender. Remove from oven and toss with the spinach leaves. Return to oven for 2 minutes, or until the spinach has wilted. Drizzle with oil and sprinkle with Parmesan cheese. Makes 2 servings. Enjoy!