1. Place the potatoes in a large pot and cover with cold water. Add a generous pinch of salt. Bring to a boil and cook until fork-tender, about 15–20 minutes. Drain and let cool slightly.

2. Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper.

3. Arrange potatoes on the prepared baking sheet. Use a potato masher or the bottom of a glass to gently flatten each potato until it is about ½ inch thick.

4. In a small saucepan, melt the butter. Stir in olive oil and minced garlic.

5. Brush each smashed potato generously with the garlic butter mixture. Season with salt and black pepper.

6. Bake in the preheated oven for 20–25 minutes, or until potatoes are golden and crispy on the edges.

7. Sprinkle parmesan cheese evenly over the potatoes during the last 5 minutes of baking. Return to the oven until the cheese is melted and golden.

8. Remove from oven, sprinkle with chopped fresh parsley, and serve immediately.