Place a rimmed baking sheet on the centre rack of the oven and preheat the oven to 425F.
Wash the fingerling potatoes to remove any dirt. Pat dry with paper towels or a clean kitchen towel, then slice each potato in half lengthwise. Add the potatoes to a large bowl, and toss with the oil, salt, thyme, garlic powder and paprika.
Wearing oven mitts, carefully remove the preheated baking sheet from the oven. Add the butter to the hot pan and use a spatula to push it around the pan to melt the butter quickly. Add the potatoes to the pan and toss with the spatula to coat in the butter. Spread the potatoes out on the pan, flipping them over if necessary so each potato is cut side down on the baking sheet.
Return the pan to the oven and roast the potatoes for 20-25 minutes or until they are tender on the inside when pierced with the tip of a sharp knife, and crispy and golden on the bottom.
Transfer the potatoes to a serving dish and garnish with the chopped green onions, if using. Serve immediately.
Keyword potatoes, roasted potatoes, roasted vegetables, Side Dish