1. In a large saucepan over high heat, place potatoes in enough water to cover; bring to a boil. Once boiling, reduce heat to medium and simmer about 20 minutes, or until potatoes are just tender. Drain and let cool slightly. 2. Preheat oven to 450°F. Coat 2 baking sheets with cooking spray. Place potatoes on baking sheet. Using a large spoon or the heel of your hand, gently press down on each potato to smash it, so it ends up about 1/2-inch thick. Make sure to keep each potato in one piece. 3. In a small bowl, combine butter, garlic, parsley, salt, and pepper; mix well. Brush mixture over potatoes, then sprinkle with Parmesan cheese. 4. Bake 15 to 20 minutes, or until potatoes are crispy and golden.