01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper or lightly grease it.
02 - Place potatoes in a large pot and cover with cold water. Add kosher salt and bring to a boil. Cook for 15 to 20 minutes until fork-tender. Drain thoroughly.
03 - Arrange cooked potatoes on the baking sheet. Using the bottom of a glass or potato masher, gently flatten each potato to approximately half an inch thickness.
04 - Combine olive oil, minced garlic, black pepper, and sea salt in a small bowl. Drizzle evenly over the smashed potatoes.
05 - Bake for 20 to 25 minutes until potatoes are golden and crispy around the edges.
06 - Remove from oven. Drizzle melted butter over each potato and sprinkle evenly with grated Parmesan. Return to oven for 2 to 3 minutes until cheese melts.
07 - Sprinkle fresh chopped parsley over the finished potatoes before serving.