Preheat your oven to broil (or grill) settings to medium-high heat (about 200°C | 400°F).

Place potatoes in a large pot of salted water. Bring to the boil; cook, covered for 30-35 minutes or until just fork-tender. Drain well.

Lightly grease a large baking sheet or tray with cooking oil spray. Arrange potatoes onto the sheet and use a potato masher to lightly flatten the potatoes in one piece.

Mix together the melted butter, minced garlic, and chopped parsley. Pour the mixture over each potato. Sprinkle with salt and pepper and lightly spray with olive oil spray.

Broil (or grill) until they are golden and crispy (about 10-15 minutes). Remove from oven, sprinkle over the grated parmesan cheese, and return to the oven until the cheese is melted.

To serve, season with a little extra salt and parsley, and serve immediately.