Place the diced potatoes in a pot and cover with water. Add 1 teaspoon kosher salt. Bring to a boil over medium-high heat. Simmer until the outer edges are tender, about 7-9 minutes.
Toss the potatoes with olive oil, extra salt, onion powder, paprika, and freshly ground black pepper. Spread them in a single layer on the prepared baking sheet or dish.
Take the cooked potatoes out of the oven. Drizzle the garlic butter sauce over them while they're hot and toss gently to coat well. Serve immediately, garnished with fresh parsley.