01 - Preheat oven to 425°F. Line a baking sheet with parchment paper or lightly grease it.
02 - Place potatoes in a large pot and cover with cold, salted water. Bring to a boil, reduce heat, and simmer for 15-20 minutes until potatoes are fork-tender. Drain well.
03 - Arrange potatoes on prepared baking sheet. Using the bottom of a glass or potato masher, gently smash each potato to approximately 1/2-inch thickness.
04 - In a small bowl, combine melted butter, olive oil, and minced garlic. Brush smashed potatoes generously with the garlic butter mixture.
05 - Sprinkle potatoes evenly with salt, pepper, and grated Parmesan cheese.
06 - Bake for 20-25 minutes until edges are golden and crispy.
07 - Remove from oven and sprinkle with fresh chives. Serve hot.