Preheat oven to 375ºF. Place halved fingerling potatoes in a single layer on a baking sheet. Mix together olive oil, melted butter and seasoning. Drizzle over potatoes and toss to coat evenly. Roast for 20-25 minutes or until fork tender. Serve hot with a dollop of sour cream or toss cooled potatoes with lemon juice and mayo for a refreshing potato salad.