Place the potatoes in a large pot of cold salted water, bring to a boil, and cook for 15-20 minutes until a fork slides in easily. Drain and let them steam dry for 5 minutes. Preheat the oven to 450°F.
Drizzle 2 tablespoons of the olive oil onto a large baking sheet. Arrange the potatoes with plenty of space between them and press each one down with the bottom of a glass until about 1/2 inch thick.
Brush the tops with the remaining olive oil and season with salt, black pepper, and garlic powder. Roast for 20 minutes until the edges are crisp and golden.
Stir the minced garlic into the melted butter and brush it over the potatoes. Sprinkle each one with dairy free parmesan and roast for another 8-10 minutes until deeply golden and crunchy.
Finish with fresh parsley and flaky sea salt. Serve hot.