01 - Preheat oven to 425°F. Line a baking sheet with parchment paper or lightly grease.
02 - In a large pot, cover potatoes with cold water and add a pinch of salt. Bring to a boil, then simmer for 15 to 20 minutes until fork-tender. Drain and cool for 3 minutes.
03 - Arrange boiled potatoes onto the baking sheet. Using a flat-bottomed glass or potato masher, gently press each potato to approximately 1/2 inch thickness.
04 - Drizzle smashed potatoes with olive oil. Evenly sprinkle with garlic powder, smoked paprika, sea salt, and black pepper. Toss gently to distribute.
05 - Place tray in oven and roast for 20 to 25 minutes, turning once halfway, until golden and crisp at the edges.
06 - Remove tray from oven. Sprinkle shredded cheddar cheese and sliced green onions evenly over potatoes. Return to oven for 3 to 5 minutes, until cheese is melted and bubbling.
07 - Finish with chopped parsley if desired. Serve immediately while hot.