01 - Preheat oven to 425°F. Line a baking sheet with parchment paper or lightly coat with oil.
02 - Place potatoes in a large pot, cover with cold water and a pinch of salt, and bring to a boil. Reduce heat and simmer for 15 to 20 minutes, until tender when pierced with a fork. Drain and allow to cool for 3 minutes.
03 - Arrange potatoes on the prepared baking sheet. Using a flat-bottomed glass or potato masher, gently press each potato to approximately 1/2-inch thick.
04 - Drizzle potatoes with olive oil and sprinkle evenly with garlic powder, smoked paprika, sea salt, and black pepper. Toss gently to ensure thorough coating.
05 - Roast potatoes for 20 to 25 minutes, turning once halfway, until edges are golden brown and crisp.
06 - Remove from oven, scatter shredded cheddar and sliced green onions over the potatoes, and return to oven for 3 to 5 minutes, until cheese melts and bubbles.
07 - Top potatoes with chopped parsley if desired. Serve immediately while hot.