Rosemary Hasselback Sweet Potatoes

1. Preheat oven to 425ºF.
2. Clean potatoes well and cut into thin slices almost to the bottom of the potato but not fully through.
3. Rub potatoes with 1 tablespoon olive oil.
4. Place on a lined baking sheet.
5. Cut butter into small pieces and place on top or in the slits of the potato.
6. Sprinkle 1 teaspoon rosemary and salt and pepper on top.
7. Bake for about 45 minutes.
8. For dressing, in a small bowl, whisk all remaining ingredients together except remaining olive oil.
9. Slowly pour in olive oil, whisking at the same time until incorporated.
10. Once potatoes are finished cooking, drizzle dressing on top and serve hot.