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 potatoes are fork-tender. Drain well.
03 - Arrange the cooked potatoes on the prepared baking sheet. Gently smash each potato to about 1/2-inch thickness using the bottom of a glass or a potato masher.
04 - In a small bowl, combine olive oil, minced garlic, black pepper, and sea salt. Drizzle over the smashed potatoes evenly.
05 - Bake for 20 to 25 minutes until potatoes are golden and crispy around the edges.
06 - Remove from oven. Drizzle with melted butter and sprinkle grated Parmesan cheese over each potato. Return to oven for 2 to 3 minutes until cheese melts.
07 - Sprinkle freshly chopped parsley over the potatoes before serving.